Dual display liquid crystal display device, method of operating the same, and mobile communication terminal including the same

• US 7,102,715 B2
• Filed: 12/19/2003
• Issued: 09/05/2006
• Est. Priority Date: 03/27/2003
• Status: Expired due to Fees

• Current Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Kang, Hoon, Kim, Kyeong Jin
• Primary Examiner(s): Chowdhury, Tarifur R.
• Application Number:
  US10/739,303
• Publication Number:
  US 20040189902A1
• Time in Patent Office: 991 Days
• Field of Search: 349/96, 349/98, 349113-115, 349/117, 349/119
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133342 for double-sided displays
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2203/09 transflective

Abstract

A dual display liquid crystal display (LCD) device includes a front light unit for supplying a light, a first polarizing plate disposed on the front light unit, a first phase compensation film disposed on the first polarizing plate, an LCD panel disposed on the first phase compensation film, a selective reflection/transmission unit disposed on the LCD panel, a second phase compensation film disposed on the selective reflection/transmission unit, and a second polarizing plate disposed on the second phase compensation film, wherein the selective reflection/transmission unit selectively reflects and transmits the incident light so that the dual display LCD device operates in reflection mode to display an image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode.

Claims

1. A dual display liquid crystal display (LCD) device, comprising:

a front light unit for supplying a light;

a first polarizing plate disposed on the front light unit;

a first phase compensation film disposed on the first polarizing plate;

an LCD panel disposed on the first phase compensation film;

a selective reflection/transmission unit disposed on the LCD panel;

a second phase compensation film disposed on the selective reflection/transmission unit; and

a second polarizing plate disposed on the second phase compensation film, wherein the selective reflection/transmission unit selectively reflects and transmits the incident light so that the dual display LCD device operates in reflection mode to display an image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode.

2. The device according to claim 1, wherein the front light unit is provided with a light source at a side thereof.

3. The device according to claim 1, wherein the first phase compensation film and the second phase compensation film have optical axes arranged along a same direction.

4. The device according to claim 1, wherein the first phase compensation film and the second phase compensation film are composed of a quarter wave plate (QWP).

5. The device according to claim 1, wherein the selective reflection/transmission unit is composed of a cholesteric liquid crystal film.

6. The device according to claim 1, wherein the LCD panel generates a phase retardation of about λ

/2 of the received light dependent upon whether or not a voltage is applied, or does not generate a phase retardation.

7. The device according to claim 1, further comprising a third phase compensation film disposed on the second polarizing plate.

8. The device according to claim 7, wherein the third phase compensation film is composed of a quarter wave plate (QWP).

9. The device according to claim 7, wherein the third phase compensation film has the same optical axis as that of the second phase compensation film.

10. The device according to claim 7, wherein the third phase compensation film has an optical axis different from that of the second phase compensation film by about 90°

.

11. A method of operating a dual display LCD device, comprising the steps of:

receiving light emitted from a front light unit and converting the received light into a circularly polarized light;

allowing the circularly polarized light to be incident into an LCD panel and controlling one of a left-handed circular polarization and right-handed circular polarization of the light transmitted through the LCD panel according to an applied voltage; and

allowing the light transmitted through the LCD panel to be incident into a selective reflection/transmission unit and selectively reflecting and transmitting the incident light at the selective reflection/transmission unit depending on the one of the left-handed circular polarization and right-handed circular polarization of the light transmitted through the LCD panel,

wherein the dual display LCD device operates in reflection mode to display an image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode.

12. A mobile communication terminal, comprising:

a dual display LCD device comprising;

a front light unit for supplying a light, a first polarizing plate disposed on the front light unit, a first phase compensation film disposed on the first polarizing plate, an LCD panel disposed on the first phase compensation film, a selective reflection/transmission unit disposed on the LCD panel, a second phase compensation film disposed on the selective reflection/transmission unit, and a second polarizing plate disposed on the second phase compensation film,

wherein the dual display LCD device selectively reflects and transmits the light applied from the selective reflection/transmission unit so that the dual display LCD device operates in a reflection mode to display an image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode;

a communication system for communicating with an external side; and

a controller for controlling the communication system and the dual display LCD device and controlling direction of displaying an image of the dual display LCD device.

13. A dual display LCD device, comprising:

a front light unit for supplying a light;

a first polarizing unit disposed on the front light unit;

an LCD panel disposed on the first polarizing unit;

a selective reflection/transmission unit disposed on the LCD panel; and

a second polarizing unit disposed on the selective reflection/transmission unit,

wherein the selective reflection/transmission unit selectively reflects and transmits the incident light so that the dual display LCD device operates in a reflection mode to display the image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode, and

wherein the first polarizing unit comprises;

a single polarizing plate; and

a single phase compensation film for generating a phase difference of about λ

/4 with respect to the light.

14. The device according to claim 13, wherein the front light unit is provided with a light source at a side thereof.

15. The device according to claim 13, wherein the phase compensation film is composed of a quarter wave plate (QWP).

16. The device according to claim 13, wherein the selective reflection/transmission unit is composed of a cholesteric liquid crystal film.

17. A dual display LCD device, comprising:

a front light unit for supplying a light;

a first polarizing unit disposed on the front light unit;

an LCD panel disposed on the first polarizing unit;

a selective reflection/transmission unit disposed on the LCD panel; and

a second polarizing unit disposed on the selective reflection/transmission unit,

wherein the selective reflection/transmission unit selectively reflects and transmits the incident light so that the dual display LCD device operates in a reflection mode to display the image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode, and

wherein the second polarizing unit comprises;

a phase compensation film for generating a phase difference of about λ

/4 with respect to the received light; and

a polarizing plate.

18. The device according to claim 17, wherein the phase compensation film is composed of a quarter wave plate (QWP).

19. A dual display LCD device, comprising:

a front light unit for supplying a light;

a first polarizing unit disposed on the front light unit;

an LCD panel disposed on the first polarizing unit;

a selective reflection/transmission unit disposed on the LCD panel;

a second polarizing unit disposed on the selective reflection/transmission unit; and

a phase compensation film disposed on the second polarizing unit,

wherein the selective reflection/transmission unit selectively reflects and transmits the incident light so that the dual display LCD device operates in a reflection mode to display the image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode.

20. The device according to claim 19, wherein the phase compensation film is composed of a quarter wave plate (QWP).

21. A mobile communication terminal, comprising:

a dual display LCD device comprising;

a front light unit for supplying a light, a first polarizing unit disposed on the front light unit, an LCD panel disposed on the first polarizing unit, a selective reflection/transmission unit disposed on the LCD panel, and a second polarizing unit disposed on the selective reflection/transmission unit, wherein the selective reflection/transmission unit selectively reflects and transmits the incident light so that the dual display LCD device operates in a reflection mode to display an image on a front side thereof in a first display mode and operates in a transmission mode to display an image on a rear side thereof in a second display mode;

a communication system for communicating with an external side; and

a controller for controlling the communication system and the dual display LCD device and controlling direction of displaying the image of the dual display LCD devices,

wherein the first polarizing unit comprises;

a single polarizing plate; and

a single phase compensation film for generating a phase difference of about λ

/4 with respect to the light.