Device capable of switching between an image display status and a mirror status, and an instrument disposed therewith

• US 7,495,719 B2
• Filed: 04/27/2001
• Issued: 02/24/2009
• Est. Priority Date: 02/28/2001
• Status: Expired due to Term

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Fuji, Gorouta, Adachi, Masaya, Tsumura, Makoto
• Primary Examiner(s): Kim; Richard H
• Application Number:
  US10/468,872
• Publication Number:
  US 20040100598A1
• Time in Patent Office: 2,860 Days
• Field of Search: 349/96, 349/74
• US Class Current: 349/96
• 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 comprising:

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 comprising 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 comprising a lighting system, a liquid crystal display panel and an image light-use polarization selection means disposed proximate to the liquid crystal display panel, wherein;

the image light-use polarization selection means transmits light of the desired image of the first polarization and absorbs light of the second polarization, and

the image display portion emits the desired image, as the image light, light of the first polarization transmitted through the image light-use polarization selection means.

2. The device of claim 1, further comprising:

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 comprising:

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.

4. The device of claim 2 or 3, 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.

5. The device of claim 4, wherein:

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.

6. The device of claim 4, 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.

7. The device of claim 1, wherein:

the transmission polarization axis variable means comprises 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 has 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.

8. The device of claim 1, 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.

9. 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.

10. 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.

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

39.1mm.

12. A device capable of switching between an image display status and a mirror status, the device comprising the following elements arranged in the following order:

a) an absorbing polarization selection member with an absorption polarization axis in a first direction and a transmission polarization axis in a second direction, wherein the first direction and the second direction are approximately perpendicular;

b) a transmissive polarization axis variable portion, wherein the polarization axis of transmitted light is not changed when no voltage is applied, and is either changed from the first direction to the second direction or from the second direction to the first direction when voltage is applied;

c) a reflective polarization selection member with a reflective polarization axis in the second direction and a transmission polarization axis in the first direction,

wherein elements a), b), and c) act as a mirror for outside light with the second polarization axis when voltage is applied to element b), and

wherein elements a), b), and c) act as a window for outside light with the second polarization axis when voltage is not applied to element b);

d) an absorbing polarization selection member with a transmission polarization axis in the first direction and an absorption polarization axis in the second direction;

e) a liquid crystal panel; and

f) a lighting system,

wherein elements d), e), and f) act as an image display portion for image light with a transmission polarization axis in the first direction when the lighting system and the liquid crystal panel are powered.

13. A device capable of switching between an image display status and a mirror status, the device comprising the following elements arranged in the following order:

a) an absorbing polarization selection member with a transmission polarization axis in a first direction and an absorption polarization axis in a second direction, wherein the first direction and the second direction are approximately perpendicular;

b) a transmissive polarization axis variable portion, wherein the polarization axis of transmitted light is not changed when no voltage is applied, and is either changed from the first direction to the second direction or from the second direction to the first direction when voltage is applied;

c) a reflective polarization selection member with a reflective polarization axis in the second direction and a transmission polarization axis in the first direction,

wherein elements a), b), and c) act as a mirror for outside light with the second polarization axis when voltage is not applied to element b), and

wherein elements a), b), and c) act as a window for outside light with the second polarization axis when voltage is applied to element b);

d) an absorbing polarization selection member with a transmission polarization axis in the first direction and an absorption polarization axis in the second direction;

e) a liquid crystal panel; and

f) a lighting system,

wherein elements d), e), and f) act as an image display portion for image light with a transmission polarization axis in the first direction when the lighting system and the liquid crystal panel are powered.