Display device

• US 6,972,815 B2
• Filed: 07/16/2003
• Issued: 12/06/2005
• Est. Priority Date: 07/19/2002
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Tsuda, Kazuhiko, Fujiwara, Sayuri, Kanbe, Makoto
• Primary Examiner(s): Dudek, James A.
• Application Number:
  US10/619,783
• Publication Number:
  US 20040013822A1
• Time in Patent Office: 874 Days
• Field of Search: 349/113, 349/114
• US Class Current: 349/114
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133711 by organic films, e.g. polymeric films
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making

Abstract

A display device includes: a display medium layer; and a first electrode and a second electrode, which face each other with the display medium layer interposed between them. The first electrode includes: a first conductive layer; and a first polymer film, which covers the first conductive layer and which makes contact with the display medium layer. The second electrode includes: a second conductive layer; and a second polymer film, which covers the second conductive layer and which makes contact with the display medium layer. At least a portion of the first conductive layer has a different work function from the second conductive layer. The number of benzene rings included in each of the first and second polymer films is 0.4 or less for a molecular weight of 100.

Claims

1. A display device comprising:

a display medium layer; and

a first electrode and a second electrode, which face each other with the display medium layer interposed between them,

wherein the first electrode includes;

a first conductive layer; and

a first polymer film, which covers the first conductive layer and which makes contact with the display medium layer,

wherein the second electrode includes;

a second conductive layer; and

a second polymer film, which covers the second conductive layer and which makes contact with the display medium layer,

wherein the first and second polymer films are alignment films, and the first and second polymer films directly contact the first and second electrodes, respectively;

wherein at least a portion of the first conductive layer has a different work function from the second conductive layer, and

wherein a variation in potential difference between potential levels of the first and second electrodes right after the device has been exposed to light is about 10% or less of a voltage that is applied to display a grey-scale tone.

5. The device of claim 1, wherein the first and second polymer films exhibit a transmittance of about 97% or more with respect to incoming light having a wavelength of about 400 nm to about 500 nm.

6. The device of claim 1, wherein the first conductive layer is a reflective conductive layer and the second conductive layer is a transparent conductive layer.

7. The device of claim 6, further comprising another transparent conductive layer, which is provided as a third conductive layer in the first electrode.

9. The device of claim 1, wherein a voltage being applied to the display medium layer for display purposes is updated at a frequency of about 45 Hz or less.

10. The device of claim 6, wherein the transparent conductive layer includes ITO, and the reflective conductive layer includes Al.

11. The device of claim 1, wherein an AC voltage, which includes an additional offset voltage and which changes its polarity at regular intervals, is applied to the display medium layer.

12. A mobile electronic appliance comprising the display device of claim 1.

2. A display device comprising:

a display medium layer;

a first electrode and a second electrode, which face each other with the display medium layer interposed between them,

wherein the first electrode includes;

a first conductive layer; and

a first polymer film, which covers the first conductive layer and which makes contact with the display medium layer,

wherein the second electrode includes;

a second conductive layer; and

a second polymer film, which covers the second conductive layer and which makes contact with the display medium layer,

wherein at least a portion of the first conductive layer has a different work function from the second conductive layer,

wherein a variation in potential difference between potential levels of the first and second electrodes right after the device has been exposed to light is about 10% or less of a voltage that is applied to display a grey-scale tone,

wherein the display medium layer includes a liquid crystal material, and

wherein the variation in potential difference has an absolute value of at most about 250 mV.

3. The device of claim 2, wherein the variation in potential difference has an absolute value of at most about 30 mV.

8. The device of claim 2, wherein the first and second polymer films are alignment films.

4. A display device comprising:

a display medium layer;

a first electrode and a second electrode, which face each other with the display medium layer interposed between them,

wherein the first electrode includes;

a first conductive layer; and

a first polymer film, which covers the first conductive layer and which makes contact with the display medium layer,

wherein the second electrode includes;

a second conductive layer; and

a second polymer film, which covers the second conductive layer and which makes contact with the display medium layer,

wherein at least a portion of the first conductive layer has a different work function from the second conductive layer,

wherein a variation in potential difference between potential levels of the first and second electrodes right after the device has been exposed to light is about 10% or less of a voltage that is applied to display a grey-scale tone, and

wherein the number of benzene rings included in each of the first and second polymer films is 0.4 or less for a molecular weight of 100.

13. The device of claim 4, wherein the first and second polymer films exhibit a transmittance of about 97% or more with respect to incoming light having a wavelength of about 400 nm to about 500 nm.

14. The device of claim 4, wherein the first conductive layer is a reflective conductive layer and the second conductive layer is a transparent conductive layer.

15. The device of claim 4, further comprising another transparent conductive layer, which is provided as a third conductive layer in the first electrode.

16. The device of claim 4, wherein the first and second polymer films are alignment films.

17. The device of claim 4, wherein a voltage being applied to the display medium layer for display purposes is updated at a frequency of about 45 Hz or less.

18. The device of claim 14, wherein the transparent conductive layer includes ITO, and the reflective conductive layer includes Al.

19. The device of claim 4, wherein an AC voltage, which includes an additional offset voltage and which changes its polarity at regular intervals, is applied to the display medium layer.

20. A mobile electronic appliance comprising the display device of claim 4.

21. The device of claim 4, wherein the display medium layer includes a liquid crystal material, and wherein the variation in potential difference has an absolute value of at most about 250 mV.

22. The device of claim 21, wherein the variation in potential difference has an absolute value of at most about 30 mV.