Photoconductive switching element, device using it, and apparatus, recording apparatus, and recording method in which the device is incorporated

• US 6,600,473 B1
• Filed: 12/28/1999
• Issued: 07/29/2003
• Est. Priority Date: 01/20/1999
• Status: Expired due to Fees

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Harada, Haruo, Arisawa, Hiroshi, Kobayashi, Hideo, Kakinuma, Takeo, Koshimizu, Minoru
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): ABDULSELAM, ABBAS I
• Application Number:
  US09/472,781
• Time in Patent Office: 1,309 Days
• Field of Search: 345/97, 345/81, 345/204, 345/206, 430/1, 430/2, 430/290, 358/471, 359/72, 359/48
• US Class Current: 345/97
• CPC Class Codes: G02F 1/1354 having a particular photoconducting structure or material
• CPC Class Codes: G02F 1/1391 Bistable or multi-stable liquid crystal cells G02F1/141 takes precedence

Abstract

The invention provides a photoconductive switching element used for light switching of a functional element driven by an AC electric field or AC current which are highly functional and inexpensive and provides a device in which such a photoconductive switching element and a functional element such as a liquid display element are combined and incorporated, and an apparatus, a recording apparatus, and a recording method which are provided with the above-mentioned device. The photoconductive switching element has at least a light transmissible electrode layer, a charge generation layer, a charge transfer layer, and a charge generation layer laminated in this order on a light transmissible substrate. The photoconductive switching element is combined with a functional element to form a device of the present invention, and the device is incorporated in an apparatus or a recording apparatus to fabricate an apparatus or a recording apparatus respectively of the present invention. In the recording method of the present invention, such a recording apparatus is used.

Claims

1. A photoconductive switching element used for switching of a functional element driven by an AC electric field or AC current, comprising:

a light transmissible substrate;

at least one light transmissible electrode layer on the light transmissible substrate;

a first charge generation layer on the at least one light transmissible electrode layer, the first charge generation layer generating at least one carrier and at least one electron when a light irradiates the first charge generation layer;

a charge transfer layer on the first charge generation layer; and

a second charge generation layer on the charge transfer layer, the second charge generation layer generating at least one carrier and at least one electron when the light is irradiated,

wherein the AC electric field or AC current is applied between the light transmissible electrode layer and a second electrode layer above the second charge generation layer.

2. The photoconductive switching element as claimed in claim 1, wherein each of the charge generation layers includes a charge generation material and the charge transfer layer includes a charge transfer material, the charge generation material and the charge transfer material are mixed at an interface between the first or second charge generation layer and the charge transfer layer so that a mixing ratio of the charge generation material and the charge transfer material changes continuously in a lamination direction.

3. The photoconductive switching element as claimed in claim 1, wherein the substrate is a plastic substrate.

4. The photoconductive switching element as claimed in claim 1, wherein each of the charge generation layer and the charge transfer layer are made from an organic material.

5. A device, comprising:

the photoconductive switching element of claim 1;

a functional element electrically connected to the photoconductive switching element; and

an electrode layer, wherein the electrode layer is electrically connected to at least one of the functional element and the photoconductive switching element.

6. The device as claimed in claim 5, wherein the photoconductive switching element and the functional element are unified in one piece.

7. The device as claimed in claim 6, wherein the functional element shows a memory characteristic.

8. The device as claimed in claim 6, wherein the functional element is a display element.

9. The device as claimed in claim 8, wherein the display element shows a memory characteristic.

10. The device as claimed in claim 8, wherein the display element is a liquid crystal display element.

11. The device as claimed in claim 10, wherein the liquid crystal display element is a bistable liquid crystal display element.

12. The device as claimed in claim 11, wherein the bistable liquid crystal element is a cholesteric liquid crystal display element.

13. A device, comprising:

the photoconductive switching element of claim 1;

a functional film for removing the DC component;

a functional element; and

an electrode layer, wherein the electrode layer is electrically connected to at least one of the functional element and the photoconductive switching element.

14. The device as claimed in claim 13, wherein the functional element is a display element.

15. The device as claimed in claim 14, wherein the functional film for removing the DC component has a capacitance component larger than that of the display element.

16. The device as claimed in claim 15, wherein the functional film for removing the DC component having a capacitance component larger than that of the display element is made of a material mainly containing an organic material selected from a group of polyvinylalcohol (PVA), polyvinylcarbazole, polyvinylacetate, polyethyleneoxide, and polybutylalcohol.

17. The device as claimed n claim 15, wherein the functional film for removing the DC component having a capacitance component larger than that of the display element is made of a material mainly containing an inorganic material selected from a group of Si—

O, Ti—

O, Al—

O, Si—

N, PZT, Ta—

O, and Al—

N.

18. An apparatus, comprising:

a device having the photoconductive switching element as claimed in claim 1 and at least one selected from a functional element showing a memory characteristic, a display element, a display element showing a memory characteristic, a liquid crystal element, a bistable liquid crystal display element and a cholesteric liquid crystal display element which is unified with photoconductive switching element;

an electrode layer, wherein the electrode layer is electrically connected to at least one of the functional element, the photoconductive switching element and the device; and

a driver detachably and electrically connected to the device for driving the device.

19. An apparatus having the device as claimed in claim 13 and a driver connected detachably and electrically to the device for driving the device.

20. A recording apparatus comprising:

the device of claim 6;

a light writing unit that emits a light onto the photoconductive switching element; and

a pulse input unit that supplies a positive pulse and a negative pulse to the device as the driving pulse that drives the device.

21. The recording apparatus as claimed in claim 20, wherein the pulse input unit applies the negative pulse as the final pulse, the positive pulse as the first pulse, or the positive pulse as the first pulse and the negative pulse as the final pulse.

22. The recording apparatus as claimed in claim 21, wherein the display element is a cholesteric liquid crystal display element, and the pulse input unit applies the negative pulse as the final pulse.

23. The recording apparatus as claimed in claim 21, wherein the device comprises a functional film for removing the DC component additionally.

24. A recording method using the recording apparatus as claimed in claim 21, comprising the steps of:

applying the positive pulse and the negative pulse to the device as the driving pulse to drive the device; and

emitting the light onto the photoconductive switching element for light writing,

wherein the negative pulse is applied as the final pulse, or the positive pulse is applied as the first pulse, or the positive pulse and a negative pulse are applied as the first pulse and as the final pulse respectively.