Unstructured Flat X-Ray Emitter for Small Focal Spots
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Solution Overview
Problem
Existing X-ray tube emitters with slit structures suffer from electrical field penetration into the slits, leading to increased tangential velocity components of electrons and resulting in larger focal spots, which is a limitation for achieving smaller focal spot sizes while maintaining fast response times.
Innovation Solution
An unstructured flat emitter with conductive fixing sections, where the emitting section has a solid surface and a spring structure to compensate for thermal expansion, combined with a heating device having an inhomogeneous temperature distribution to ensure homogeneous electron emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If slit structures are used in the emitter to create electrical current paths, then the electrical resistance is increased and device size is reduced, but the electrical field penetrates into the slits causing increased tangential velocity components and larger focal spots
Solution Approach 1:
The invention extracts and removes the harmful slit structure from the emitter while retaining the essential function of current conduction. By eliminating the slits that cause electrical field penetration and tangential velocity components, the patent achieves smaller focal spots without compromising the electrical resistance requirement through alternative means (contactless heating)
Solution Approach 2:
The patent introduces an intermediary heating device that transfers thermal energy to the emitter without requiring direct electrical contact through slits. This mediator (heating device) enables current path creation without the harmful structural features of traditional slit-based emitters
2Speed
If the emitter thickness is reduced to achieve fast thermal response times, then the response time is improved, but the mechanical stability and thermal homogeneity are compromised
Solution Approach 1:
The invention segments the heating function from the emitter structure itself, using a separate heating device with controlled temperature distribution. This allows the emitter to be optimized for mechanical stability while the heating device provides the necessary thermal response, resolving the contradiction between thickness and stability
Solution Approach 2:
The heating device implements local quality by providing an inhomogeneous temperature distribution during heating that compensates for thermal gradients. This enables fast thermal response in specific regions while maintaining overall mechanical stability and thermal homogeneity in the emitter
3Power
If high current is applied to achieve high power, then the power output is increased, but the thermal expansion and deformation of the emitter increase
Solution Approach 1:
The heating device acts as an intermediary that transfers thermal energy more efficiently and uniformly to the emitter, reducing localized thermal stress and deformation while maintaining high power output capability
Solution Approach 2:
The invention changes the heating parameters by using controlled temperature distribution and heating rates, which reduces thermal shock and emitter deformation while still achieving the necessary high power output for X-ray generation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves significantly smaller focal spot sizes and maintains fast response times, improving image quality without compromising mechanical stability or thermal homogeneity, essential for medical applications.
Implementation Method 1
a heating device (27) to heat the emitter (26), characterized in that the heating device (27) is designed to generate an inhomogeneous temperature distribution
Implementation Method 2
the fixing sections (31-34) have a spring structure... the spring structure of the fixing sections may compensate this expansion
Implementation Method 3
a flat foil with an emitting section... directly heated thin flat emitters
Data Source
AI summary
It is described an emitter (26, 40) for X-ray tubes comprising: a flat foil with an emitting section (30, 46); and at least two electrically conductive fixing sections (31-34; 41-44); wherein the emitting section (30, 46) is unstructured.