Display device and electronic equipment employing the same

• US 6,768,481 B2
• Filed: 07/22/2002
• Issued: 07/27/2004
• Est. Priority Date: 07/25/1997
• Status: Expired due to Term

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Inoue, Akira, Ozawa, Yutaka, Iijima, Chiyoaki, Maeda, Tsuyoshi, Yamazaki, Katsunori
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): ZAMANI, ALI A
• Application Number:
  US10/200,610
• Publication Number:
  US 20030020678A1
• Time in Patent Office: 736 Days
• Field of Search: 345/87, 345/89, 345/90, 345/96, 345/99, 345/103, 345/100, 349/9, 349/57, 349/121, 349/117, 349/104, 349/5, 359/487
• US Class Current: 345/87
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/367 with a nonlinear element in series with the liquid crystal cell, e.g. a diode, or M.I.M. element

Abstract

An ON/OFF control signal 105 directive of turning ON in a transmissive display mode or turning OFF in a reflective display mode is output by an ON/OFF state controlling means 111 to a light source 115. The ON/OFF control signal 105 is also output to a data signal converting means 104, and the data signal converting means 104 converts a data signal 102 into a data signal 103 in synchronization with the switching of ON and OFF of the light source 115 so as to prevent positive-negative inversion of the display on a liquid crystal panel 114. A data signal potential supplying means 112 supplies a potential of a data signal based on the data signal 103 to a data signal line 113 so as to drive the liquid crystal panel 114.

Claims

1. A display device that displays in each of a reflective display mode using external light and a transmissive display mode using internal light, a gray scale of the display device being prepared according to image data prepared for use in each mode thereof, the display device comprising:

a first polarized light separating member that permits a first light component polarized to a first direction to pass therethrough and permits a light component other than the first light component to reflect thereagainst or be absorbed thereinto;

a second polarized light separating member that permits a second light component polarized to a second direction to pass therethrough and permits a light component other than the second light component to reflect thereagainst or be absorbed thereinto;

a variable transmission polarization axis member disposed between the first polarized light separating member and the second polarized light separating member, the variable transmission polarization axis member controlling a transmission polarization axis that is switchable between the reflective display mode and the transmissive display mode and being changeable to range from the first direction to the second direction according to the image data in each of the reflective and transmissive modes; and

a driving circuit connected to the variable transmission polarization axis member, the driving circuit being operable to apply first image data to the variable transmission polarization axis member in one of the reflective and transmissive display modes, and to apply second image data to the variable transmission polarization axis member in the other of the reflective and transmissive display modes;

wherein the second image data has preset potential which becomes approximately the same as light intensity when the first image data is applied.

2. A transflective display device according to claim 1, the driving voltage changing means changing the image data in synchronization with an ON/OFF control signal instructing the ON/OFF state of the light source.

3. A display device according to claim 1, the variable transmission polarization axis member comprising:

a data signal line;

a scanning signal line; and

a driven region formed at an intersection of the data line and the signal line,

the transmission polarization axis of the driven region being controlled by the driving voltage applied between the data line and the signal line.

4. A display device according to claim 3,

the driving circuit including a data signal potential supplying member that supplies an electrical potential of a data signal to the variable transmission polarization axis member, and

the driving circuit including a data signal converting member for changing the data signal applied to the data line in synchronization with an ON/OFF control signal controlling an ON/OFF state of the internal light.

5. A display device according to claim 4, the data signal converting member including an inverting member for inverting the data signal in synchronization with the ON/OFF control signal.

6. A display device according to claim 1, the second polarized light separating member comprising a reflective polarizer that allows the second light component polarized in the second direction to be transmitted, while the reflective polarizer reflects light components polarized in a direction orthogonal to the second direction.

7. A display device according to claim 6, the reflective polarizer comprising a laminate composed of a first layer having birefringence and a second layer that has a refractive index substantially equal to one of a plurality of refractive indexes of the first layer and that has no birefringence, the first and second layers being stacked alternately.

8. A display device according to claim 1, the second polarized light separating member allowing the second light component polarized in the second direction to be transmitted with respect to the light in an almost entire wavelength range of a visible light region, while the second polarized light separating member reflects a light component polarized in a direction orthogonal to the second direction.

9. A display device according to claim 1, the first polarized light separating member comprising a polarizer for allowing the first light component polarized in the first direction to be transmitted and absorbing a light component polarized in a direction orthogonal to the first direction.

10. A display device according to claim 1, further comprising a semi-transmissive light absorption layer located between the second polarized light separating member and a source of the internal light.

11. A display device according to claim 10, a transmittance of the semi-transmissive light absorption layer ranging from 5% to 80%.

12. A display device according to claim 1, further comprising a polarizing member which has a transmission axis roughly aligned with the second direction and which is located between the second polarized light separating member and a source of the internal light.

13. A display device according to claim 1, further comprising a transmissive light diffusion layer located between a source of the internal light and the second polarized light separating member.

14. A display device according to claim 1, further comprising a color filter.

15. A display device according to claim 3, further comprising a nonlinear element for the intersection.

16. A display device according to claim 3, the driving circuit including:

a scanning signal supplying member for supplying a scanning signal; and

a data signal supplying member for supplying a data signal, at least one of the scanning signal and the data signal being controlled by a driving voltage changing member in synchronization with an ON/OFF control signal controlling an ON/OFF state of the internal light.

17. A display device according to claim 16, the driving voltage changing member including:

a scanning signal potential controlling member for changing an electrical potential of the scanning signal in synchronization with the ON/OFF control signal.

18. A display device according to claim 17, the scanning signal potential controlling member including:

a first common potential output unit for outputting a predetermined electrical potential; and

a first converted potential output unit for outputting an electrical potential based on the ON/OFF control signal,

the scanning signal potential controlling member outputting a sum of electrical potentials from the first common potential output unit and the first converted potential output unit to the scanning signal supplying member.

19. A display device according to claim 16, the driving voltage changing member including:

a data signal potential controlling member for changing the electrical potential of the data signal in synchronization with the ON/OFF control signal.

20. A display device according to claim 19, the data signal potential controlling member including:

an image signal converting unit for converting an image signal corresponding to the image data and outputting an electrical potential of the converted image signal;

a third common potential output unit for outputting a predetermined electrical potential;

a gray scale controlling unit for outputting an electrical potential based on the ON/OFF control signal and an electrical potential corresponding to gray scale information of the image data; and

the data signal potential controlling member outputting a sum of electrical potentials from the image signal converting unit, the third common potential output unit, and the gray scale controlling unit to the data signal supplying member.

21. A display device according to claim 1, the driving circuit including:

a scanning signal supplying member for supplying a scanning signal; and

a data signal supplying member for supplying the data signal, at least one of the scanning signal and the data signal being controlled by a driving voltage changing member in synchronization with an ON/OFF control signal controlling an ON/OFF state of the internal light.

22. Electronic equipment comprising the display device described in claim 1.

33. A transflective display according to claim 1, the variable transmission polarization axis member is the liquid crystal panel.

23. A driving method for a display device that displays in each of a reflective display mode using external light and a transmissive display mode using internal light, a gray scale of the display device being prepared according to image data for use in each mode thereof, the method comprising:

providing a first polarized light separating member that permits a first light component polarized to a first direction to pass therethrough and permits a light component other than the first light component to reflect thereagainst or be absorbed thereinto;

providing a second polarized light separating member that permits a second light component polarized to a second direction to pass therethrough and permits a light component other than the second light component to reflect thereagainst or be absorbed thereinto;

disposing a variable transmission polarization axis member between the first polarized light separating member and the second polarized light separating member, the variable transmission polarization axis member controlling a transmission polarization axis that is switchable between the reflective display mode and the transmissive display mode and being changeable to range from the first direction to the second direction according to the image data in each of the reflective and transmissive display modes; and

connecting a driving circuit to the variable transmission polarization axis member and applying first image data from the driving circuit to the variable transmission polarization axis member in one of the reflective and transmissive display modes, and applying second image data from the driving circuit to the variable transmission polarization axis member in the other of the reflective and transmissive display modes;

wherein the second image data has preset potential which becomes approximately the same as light intensity when the first image data is applied.

24. A driving method for a display device according to claim 23;

the driving voltage changing step changing the driving voltage in synchronization with the ON/OFF control signal.

25. A driving method for a display device according to claim 24, the variable transmission polarization axis member comprising:

a data signal line for receiving a data signal;

a scanning signal line for receiving a scanning signal; and

a driven region formed at an intersection of the data line and the signal line,

the driving voltage changing step changing an electrical potential of the data signal, according to the image data, supplied to the data signal line.

26. A driving method for a display device according to claim 25,

the driving step including a data signal potential supplying step that supplies an electrical potential of the data signal to the variable transmission polarization axis member;

and

the driving voltage changing step including a data signal converting step for changing the data signal applied to the data line in synchronization with the ON/OFF control signal.

27. A driving method for a display device according to claim 26, the data signal converting step including an inverting step for inverting the data signal in synchronization with the ON/OFF control signal.

28. A driving method for a display device according to claim 25, the driving voltage changing step comprising:

a scanning signal supplying step for supplying the scanning signal; and

a data signal supplying step for supplying a data signal,

at least one of the scanning signal and the data signal being controlled, in synchronization with the ON/OFF control signal, by the driving voltage changing member.

29. A driving method for a display device according to claim 28, wherein the driving voltage switching step includes a scanning signal potential controlling step that makes setting so that a potential of the scanning signal supplied by the scanning signal supplying step when the light source is OFF is different from a potential of the scanning signal supplied when the light source is ON.

30. A driving method for a display device according to claim 28, wherein the driving voltage switching step includes a data signal potential controlling step that makes setting so that a potential of the data signal supplied by the data signal supplying step when the light source is OFF is different from a potential of the data signal supplied when the light source is ON.

34. A driving method for a display device according to claim 23, the variable transmission polarization axis member is the liquid crystal panel.

31. A transflective display device having a gray scale controlled according to image data prepared for use in either a reflective display mode or a transmissive display mode, the display device comprising:

a first member passing a first light component polarized to a first direction and reflecting or absorbing a light component other than the first light component;

a second member passing a second light component polarized to a second direction and reflecting or absorbing a light component other than the second light component;

a third member disposed between the first member and the second member, the third member controlling a transmission polarization axis that is switchable between the reflective and transmissive display modes and rangeable from the first direction to the second direction according to the image data in each of the reflective and transmissive display modes; and

a driving circuit connected to the third member, the driving circuit being operable to apply first image data to the third member in one of the reflective and transmissive modes, and to apply second image data to the third member in the other of the reflective and transmissive modes;

wherein the second image data has preset potential which becomes approximately the same as light intensity when the first image data is applied.

35. A transflective display device according to claim 31, the third member is the liquid crystal panel.

32. In a transflective display device having:

a first polarized light separating member that permits a first light component polarized to a first direction to pass therethrough and permits a light component other than the first light component to reflect thereagainst or be absorbed thereinto;

a second polarized light separating member that permits a second light component polarized to a second direction to pass therethrough and permits a light component other than the second light component to reflect thereagainst or be absorbed thereinto;

a variable transmission polarization axis member disposed between the first polarized light separating member and the second polarized light separating member, the variable transmission polarization axis member controlling a transmission polarization axis that is switchable between the reflective and transmissive display modes and being changeable to range from the first direction to the second direction according to the image data in each of the reflective and transmissive display modes; and

a driving circuit connected to the variable transmission polarization axis member;

the improvement comprising;

operating the driving circuit to apply first image data to the variable transmission polarization axis member in one of the reflective and transmissive modes, and to apply second image data to the variable transmission polarization axis member in the other of the reflective and transmissive modes;

wherein the second image data has preset potential which becomes approximately the same as light intensity when the first image data is applied.

36. A transflective display device according to claim 32, the variable transmission polarization axis member is the liquid crystal panel.