Luminescent screen and image-converter tubes utilizing such a screen

• US 4,023,039 A
• Filed: 01/23/1975
• Issued: 05/10/1977
• Est. Priority Date: 01/29/1974
• Status: Expired due to Term

• Current Assignee: Thomson-CSF
• Original Assignee: Thomson-CSF
• Inventors: Sagnard, Jean, Galves, Jean Pierre
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Chin, Tommy P.
• Application Number:
  US05/543,277
• Time in Patent Office: 838 Days
• Field of Search: 250/483, 250/361, 250/486, 250/487, 250/488, 250/362, 250/364, 250/367, 250/213 VT, 350/126, 350/9, 350/8
• US Class Current: 250/486.1
• CPC Class Codes: G01T 1/1645 using electron optical imaging means, e.g. image intensifier tubes, coordinate photomultiplier tubes, image converter
• CPC Class Codes: H01J 29/385 Photocathodes comprising a layer which modified the wave length of impinging radiation

Abstract

In order to avoid losses in definition and contrast which are observed in image-converter tubes as a consequence of the light scatter taking place within the body of the scintillators of the input screens of these tubes, when said scintillators occur in the form of a continuous layer of material, the present invention provides for the formation within a layer of microscopic channels which are transversely disposed, the channels being formed by covering the substrate, prior to the deposition of the scintillator thereon, with a layer of a granular material, preferably glass balls. Application to radiology and scintillography.

Claims

1. A luminescent screen comprising a layer of luminescent material applied to a substrate characterized in that between said layer and said substrate there is arranged a layer of a granular material which consists of a single layer of glass balls (4) separate from each other by interstices (5) whereby islands of luminescent material separated by microscopic channels (6) are formed in the luminescent layer.

2. A luminescent screen as claimed in claim 1, characterized in that said balls have a diameter ranging between 20 and 70/um.

3. A luminescent screen as claimed in claim 1, characterized in that said luminescent material is an alkaline halide.

4. A luminescent screen as claimed in claim 3, characterized in that said luminescent material is cesium iodide, CsI.

5. A screen according to claim 1 for an X-ray image converter tube, further comprising within a evacuted envelope an output screen, and said luminescent screen being provided with a layer of photosensitive material characterized in that said layer of photosensitive material is deposited upon said layer of luminescent material.

6. An image-converter tube for radioscopic images, comprising an input screen subjected to the incident X-ray radiation and an output screen opposite the former upon which output screen there is formed a visible image of said radiation, characterized in that said input screen is a screen as claimed in claim 5.