Radiation imaging device

• US 7,847,258 B2
• Filed: 07/18/2008
• Issued: 12/07/2010
• Est. Priority Date: 07/26/2007
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Shen, Rui, Yaegashi, Hiroyuki
• Primary Examiner(s): Porta; David P
• Assistant Examiner(s): Gaworecki; Mark R
• Application Number:
  US12/176,034
• Publication Number:
  US 20090026379A1
• Time in Patent Office: 872 Days
• Field of Search: 250/208.1, 250/336.1, 250/370.01, 250/370.08, 250/370.09, 250/370.11
• US Class Current: 250/370.08
• CPC Class Codes: G01T 1/2006 using a combination of a scintillator and photodetector which measures the means radiation intensity

Abstract

A radiation imaging device 12 has a phosphor film 8; a photoelectric conversion portion 13 including an upper electrode 6, a lower electrode 2, and a photoelectric conversion film 4 disposed between the electrodes; a signal output portion 14 including a field effect thin film transistor 10 having an active layer 24 formed from an amorphous oxide and that outputs a signal corresponding to electric charges generated by the photoelectric conversion portion; and a substrate 1 on which the signal output portion, the photoelectric conversion portion and the phosphor film are formed in this order. Each of pixel portions is made up of the signal output portion, the photoelectric conversion portion and the phosphor film, and the signal output portion and the photoelectric conversion portion in each of the pixel portions are formed so as to have an overlapping portion in a thickness direction.

Claims

1. A radiation imaging device, comprising:

a phosphor film that emits light by absorbing radiation transmitted through an imaging target;

a photoelectric conversion portion that includes an upper electrode, a lower electrode, and a photoelectric conversion film disposed between the upper and lower electrodes, the photoelectric conversion film containing an organic photoelectric conversion material that absorbs light emitted from the phosphor film;

a signal output portion that includes a field effect thin film transistor having an active layer formed from an amorphous oxide and that outputs a signal corresponding to electric charges generated by the photoelectric conversion portion; and

a substrate on which the signal output portion, the photoelectric conversion portion and the phosphor film are formed in this order, wherein

a plurality of pixel portions are arranged on the substrate, each of which is made up of a part of the signal output portion, the photoelectric conversion portion and the phosphor film, and the respective parts of the signal output portion and the photoelectric conversion portion in each of the pixel portions are formed so as to have an overlapping portion in a thickness direction.

2. The radiation imaging device of claim 1, wherein the amorphous oxide is an oxide containing at least one selected from the group consisting of In, Ga and Zn.

3. The radiation imaging device of claim 1, wherein the amorphous oxide is an oxide containing at least two selected from the group consisting of In, Ga and Zn.

4. The radiation imaging device of claim 1, wherein the amorphous oxide is an oxide containing In, Ga and Zn.

5. The radiation imaging device of claim 1, wherein a difference between an absorption peak wavelength of the organic photoelectric conversion material and an emission peak wavelength with respect to the radiation of the phosphor film is 5 nm or less.

6. The radiation imaging device of claim 1, wherein the organic photoelectric conversion material is a quinacridone-based organic compound or a phthalocyanine-based organic compound.

7. The radiation imaging device of claim 1, wherein the phosphor film contains cesium iodide.

8. The radiation imaging device of claim 1, wherein the phosphor film absorbs X-rays to emit light.

9. The radiation imaging device of claim 1, wherein the phosphor film contains cesium iodide to which titanium has been added.

10. The radiation imaging device of claim 1, wherein the lower electrode is divided in correspondence with each of pixel portions, and the photoelectric conversion film, the upper electrode and the phosphor film are respectively formed without division and are shared by the plurality of pixel portions arranged on the substrate.

11. The radiation imaging device of claim 1, wherein the upper electrode is formed of ITO.

12. The radiation imaging device of claim 1, wherein, between the lower electrode and the photoelectric conversion film, an electric charge blocking film is provided that, when a bias voltage is applied between the lower electrode and the upper electrode, inhibits electric charges from being injected from the lower electrode to the photoelectric conversion film.

13. The radiation imaging device of claim 1, wherein, between the upper electrode and the photoelectric conversion film, an electric charge blocking film is provided that, when a bias voltage is applied between the lower electrode and the upper electrode, inhibits electric charges from being injected from the upper electrode to the photoelectric conversion film.

14. The radiation imaging device of claim 1, wherein the substrate is a flexible substrate.