Device capable of switching between image display status and a mirror status, and equipment provided therewith

• US 20040100598A1
• Filed: 08/25/2003
• Published: 05/27/2004
• Est. Priority Date: 02/28/2001
• Status: Active Grant

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Adachi, Masaya, Tsumura, Makoto, Fuji, Gorouta
• Granted Patent: US 7,495,719 B2
• Time in Patent Office: Days
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 1/13475 in which at least one liquid crystal cell or layer is doped with a pleochroic dye, e.g. GH-LC cell G02F1/13476 takes precedence
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable

Abstract

There is provided a device capable of switching between a state that displays a high-quality image and a mirror status in which is obtained an easy-to-view reflection image suitable for a person to view his/her own face or figure. An image display portion 1000 that emits image light 3001, reflective polarization selection means 300 that transmits a first linear polarization component emitted from the image display portion 1000 and reflects a second linear polarization component, whose polarization axis is orthogonal to that of the first linear polarization component, a transmission polarization axis variable portion 400 capable of selecting between one of a state that changes the polarization axis of incident linearly polarized light and a state that does not change the polarization axis of incident linearly polarized light, and a polarization selection member 500 which, of the incident light, absorbs the first linear polarization component and transmits the second linear polarization component, whose polarization axis is orthogonal to that of the first linear polarization component, are disposed in this order. In this case, absorbing polarization selection means 208 is disposed at the image display portion 1000, and the first linear polarization is emitted as the image light.

Claims

1. A device capable of switching between an image display status and a mirror status, the device including an image display portion that emits image light for displaying a desired image and a mirror function portion that is superposed on the image display portion and is capable of being switched between an image transmittance state that transmits the image light and a mirror status that reflects outside light,

the mirror function portion including reflective polarization selection means, transmission polarization axis variable means, and absorbing polarization selection means successively disposed from the image display portion side, with the reflective polarization selection means transmitting a first polarization of a predetermined polarization axis and reflecting a second polarization whose polarization axis intersects that of the first polarization, the transmission polarization axis variable means being capable of switching between a state that transmits by changing the incident first polarization to the second polarization and a state that transmits without changing the polarization axis of the incident light, and the absorbing polarization selection means transmitting one of the first polarization and the second polarization and absorbing the other, and

the image display portion being disposed with image light-use polarization selection means that transmits the first polarization and absorbs the second polarization, the image display portion emitting, as the image light, the first polarization transmitted through the image light-use polarization selection means.

2. The device of claim 1, further including switching means for switching the mirror function portion between the image transmittance state and the mirror status, wherein the switching means switches the mirror function portion to the image transmittance state by switching the transmission polarization axis variable means to a state that changes the first polarization to the second polarization and switches the mirror function portion to the mirror status by switching the transmission polarization axis variable means to a state that transmits without changing the incident polarization axis.

3. The device of claim 1, further including switching means for switching the mirror function portion between the image transmittance state and the mirror status, wherein the switching means switches the mirror function portion to the image transmittance state by switching the transmission polarization axis variable means to a state that transmits without changing the incident polarization axis and switches the mirror function portion to the mirror status by switching the transmission polarization axis variable means to a state that changes the first polarization to the second polarization.

8. The device of claim 2, 3, 5 or 6, wherein the image display portion is capable of being switched to a state in which the image light is not emitted, and when the switching means switches the mirror function portion to the mirror status, the switching means switches, in conjunction therewith, the image display portion to the state in which the image light is not emitted.

9. The device of claim 8, wherein the image display portion includes a lighting system and a liquid crystal element, and the switching means turns the lighting system off or switches the liquid crystal element to a dark display in order to switch the image display portion to the state in which the image light is not emitted.

10. The device of claim 8, wherein the transmission polarization axis variable means has a configuration that is capable of being switched to a state that transmits only through a partial region without changing the incident polarization axis, and

the switching means switches a display of the image display portion of a portion overlapping with the partial region to a dark display when the transmission polarization axis variable means is switched to the state that transmits only through the partial region without changing the incident polarization axis and the image light is not emitted from the partial region.

11. The device of claim 1, 4 or 7, wherein the transmission polarization axis variable means includes a liquid crystal layer and an electrode for applying an electric field in a thickness direction of the liquid crystal layer, the liquid crystal layer having a configuration in which a long axis direction of liquid crystal molecules is continuously twisted 90°

in the thickness direction when the electric field is not applied and in which the long axis direction of the liquid crystal molecules becomes parallel to the thickness direction when the electric field is applied, and, when the mirror function portion is in the mirror status, the transmission polarization axis variable means is in a state that applies the electric field to the liquid crystal layer.

12. The device of claim 1, 4 or 7, wherein the transmission polarization axis variable means includes a liquid crystal layer and an electrode for applying an electric field in a thickness direction of the liquid crystal layer, the liquid crystal layer having a configuration in which a long axis direction of liquid crystal molecules is continuously twisted 90°

in the thickness direction when the electric field is not applied and in which the long axis direction of the liquid crystal molecules becomes parallel to the thickness direction when the electric field is applied, and, when the mirror function portion is in the mirror status, the transmission polarization axis variable means is in a state that does not apply the electric field to the liquid crystal layer.

13. The device of claim 1, wherein, when P1 represents the degree of polarization of the image light-use polarization selection means and P2 represents the degree of polarization of the absorbing polarization selection means, the relationship of 0.966≦

P1≦

0.995≦

P2 is satisfied.

14. The device of claim 1, wherein, when P1 represents the degree of polarization of the image light-use polarization selection means and P2 represents the degree of polarization of the absorbing polarization selection means, the relationship of 0.966≦

P2≦

0.995≦

P1 is satisfied, and when the mirror function portion is switched to the mirror status, the image display portion is switched, in conjunction therewith, to a state in which the image light is not emitted.

16. The device of claim 1, 4 or 7, wherein a size of a region serving as the mirror status of the mirror function portion is at least 58.6 mm×

39.1 mm.

17. The device of claim 1, wherein the image display portion includes an organic electroluminescence display element, with a phase-difference plate and the image light-use polarization selection means being disposed between an emission layer of the organic electroluminescence display element and the reflective polarization selection means.

4. A device capable of switching between an image display status and a mirror status, the device including an image display portion that emits image light for displaying a desired image and a mirror function portion that is superposed on the image display portion and is capable of being switched between an image transmittance state that transmits the image light and a mirror status that reflects outside light,

the mirror function portion including first reflective polarization selection means, transmission polarization axis variable means, second reflective polarization selection means, and variable polarization selection means successively disposed from the image display portion side, with the first reflective polarization selection means transmitting a first polarization of a predetermined polarization axis and reflecting a second polarization whose polarization axis intersects that of the first polarization, the transmission polarization axis variable means being capable of switching between a state that transmits by changing the incident first polarization to the second polarization and a state that transmits without changing the polarization axis of the incident light, the second reflective polarization selection means reflecting one of the first polarization and the second polarization and transmitting the other, and the variable polarization selection means being capable of switching between a state that absorbs one of the first polarization and the second polarization and transmits the other and a state that transmits all polarization components, and

the image display portion being disposed with image light-use polarization selection means that transmits the first polarization and absorbs the second polarization, the image display portion emitting, as the image light, the first polarization transmitted through the image light-use polarization selection means.

5. The device of claim 4, further including switching means for switching the mirror function portion between the image transmittance state and the mirror status, wherein the switching means switches the mirror function portion to the image transmittance state by switching the transmission polarization axis variable means to a state that changes the first polarization to the second polarization and switching the variable polarization selection means to a state that absorbs the first polarization and transmits the second polarization and switches the mirror function portion to the mirror status by switching the transmission polarization axis variable means to a state that transmits without changing the incident polarization axis and switching the variable polarization selection means to a state that transmits all of the polarization components.

6. The device of claim 4, further including switching means for switching the mirror function portion between the image transmittance state and the mirror status, wherein the switching means switches the mirror function portion to the image transmittance state by switching the transmission polarization axis variable means to a state that transmits without changing the incident polarization axis and switching the variable polarization selection means to a state that absorbs the second polarization and transmits the first polarization and switches the mirror function portion to the mirror status by switching the transmission polarization axis variable means to a state that changes the first polarization to the second polarization and switching the variable polarization selection means to a state that transmits all of the polarization components.

15. The device of claim 4 or 7, wherein the first reflective polarization selection means is disposed so that an interval between the first reflective polarization selection means and the second reflective polarization selection means is 0.11 mm or less.

7. A device capable of switching between an image display status and a mirror status, the device including an image display portion that emits image light for displaying a desired image and a mirror function portion that is superposed on the image display portion and is capable of being switched between an image transmittance state that transmits the image light and a mirror status that reflects outside light,

the mirror function portion including first reflective polarization selection means, transmission polarization axis variable means, and second reflective polarization select ion means successively disposed from the image display portion side, with the first reflective polarization selection means transmitting a first polarization of a predetermined polarization axis and reflecting a second polarization whose polarization axis intersects that of the first polarization, the transmission polarization axis variable means being capable of switching between a state that transmits by changing the incident first polarization to the second polarization to transmit the second polarization and a state that transmits without change the polarization axis of the incident light, and the second reflective polarization selection means reflecting one of the first polarization and the second polarization and transmitting the other, and

the image display portion being disposed with image light-use polarization selection means that transmits the first polarization and absorbs the second polarization, the image display portion emitting, as the image light, the first polarization transmitted through the image light-use polarization selection means.

18. A display device disposed with an image display portion that emits light including a first polarization state and a mirror function portion that is superposed on the image display portion and is capable of selecting between one of an image display status that transmits image light from the image display member and a mirror status that reflects light proceeding from the outside to the image display member,

wherein, when the mirror function portion is switched to the mirror status, an emission state of the image display member is switched to a non-emission state in conjunction therewith.

19. The display device of claim 18, wherein the image display portion includes a pair of transparent substrates joined with a constant gap therebetween, a liquid crystal layer sandwiched between the transparent substrates, a pixel electrode group disposed in a matrix formed by a transparent electrode on at least one of the pair of transparent substrates, display-use polarization selection means that is disposed at a viewing side of the liquid crystal layer, transmits the first linear polarization component, and absorbs the second linear polarization component, a polarizing plate disposed at an undersurface side of the liquid crystal layer, and a lighting system disposed at a rear surface thereof, and

the switching means turns the lighting system off when the mirror function portion is in the mirror status.

20. The display device of claim 18, wherein the image display portion includes a pair of transparent substrates joined with a constant gap therebetween, a liquid crystal layer sandwiched between the transparent substrates, a pixel electrode group disposed in a matrix formed by a transparent electrode on at least one of the pair of transparent substrates, display-use polarization selection means that is disposed at a viewing side of the liquid crystal layer, transmits the first linear polarization component, and absorbs the second linear polarization component, a polarizing plate disposed at an undersurface side of the liquid crystal layer, and a lighting system disposed at a rear surface thereof, and

the switching means switches the liquid crystal layer of a region of the image display member overlapping with a region of the mirror status to a dark display when the mirror function portion is in the mirror status.

21. An instrument disposed with a display device, the display device including an image display portion that emits image light for displaying a desired image and a mirror function portion that is superposed on the image display portion and is capable of being switched between an image transmittance state that transmits the image light and a mirror status that reflects outside light,

the mirror function portion including reflective polarization selection means, transmission polarization axis variable means, and absorbing polarization selection means successively disposed from the image display portion side, with the reflective polarization selection means transmitting a first polarization of a predetermined polarization axis and reflecting a second polarization whose polarization axis intersects that of the first polarization, the transmission polarization axis variable means being capable of switching between a state that transmits by changing the incident first polarization to the second polarization and a state that transmits without changing the polarization axis of the incident light, and the absorbing polarization selection means transmitting one of the first polarization and absorbing the second polarization and

the image display portion being disposed with image light-use polarization selection means that transmits the first polarization and absorbs the second polarization, the image display portion emitting, as the image light, the first polarization transmitted through the image light-use polarization selection means.

22. A device capable of switching between an image display status and a mirror status, the device including an image display portion that emits image light for displaying a desired color image and a switching function portion superposed on the image display portion,

the switching function portion being capable of switching between a state that transmits the image light of the image display portion to the outside and displays a color image at the outside and a state that changes incident outside light to a polarization state reflected on the image display portion in order to switch the image display portion to the mirror status, the switching function portion including transmission polarization axis variable means and absorbing polarization selection means successively disposed from the image display portion side, with the transmission polarization axis variable means having a configuration that is capable of switching between a state that transmits by changing, when a first polarization of a predetermined polarization axis is made incident thereat, the first polarization to a second polarization whose polarization axis intersects that of the first polarization and a state that transmits without changing the polarization axis of the incident light, and the absorbing polarization selection means transmitting one of the first polarization and the second polarization and absorbing the other,

the image display portion having a configuration that conducts color display by a field-sequential color display system, and

the image display portion including reflective polarization selection means that transmits the first polarization and reflects the second polarization, with the image display portion generating the image light of a color of the first polarization by the first polarization being transmitted through the reflective polarization selection means.