Sensor unit, radiation detector, method of manufacturing sensor unit, and method using sensor unit
Some embodiments include a sensor unit with a conversion element and a readout substrate. The conversion element has imaging pixels and each imaging pixel is configured to directly convert radiation into an electrical charge. Each imaging pixel has a charge collection electrode. The imaging pixels have first imaging pixels and second imaging pixels. The readout substrate has a plurality of readout pixels arranged in a grid. Each readout pixel is connected to an associated imaging pixel by means of an interconnection at a connection position on the charge collection electrode. The second imaging pixels are shifted in a shifting direction relative to the first imaging pixels. The connection positions, in relation to the charge collection electrodes, are different between the first imaging pixels and the second imaging pixels.
1. A sensor unit for a radiation detector, the sensor unit comprising:
a conversion element comprising a plurality of imaging pixels, each imaging pixel being configured to directly convert radiation into an electrical charge, each imaging pixel comprising a charge collection electrode, and the imaging pixels comprising first imaging pixels and second imaging pixels; and
a readout substrate comprising a plurality of readout pixels arranged in a grid, each readout pixel being connected to an associated imaging pixel by means of an interconnection at a connection position on the charge collection electrode;
wherein the second imaging pixels are shifted in a shifting direction relative to the first imaging pixels; and
wherein the connection positions in relation to the charge collection electrodes are different between the first imaging pixels and the second imaging pixels.
2. The sensor unit of claim 1 , wherein:
the shifting direction is substantially perpendicular to a scanning direction of the sensor unit.
3. The sensor unit of claim 1 , wherein:
the readout pixels are arranged in a matrix comprising a plurality of readout rows and a plurality of readout columns, the readout rows being substantially perpendicular to the readout columns and substantially parallel with the shifting direction.
4. The sensor unit of claim 1 , wherein:
the first imaging pixels are arranged in first rows and the second imaging pixels are arranged in second rows, each of the first rows and the second rows being substantially parallel with the shifting direction.
5. The sensor unit of claim 4 , wherein:
each first row and each second row is substantially aligned with a respective readout row.
6. The sensor unit of claim 5 , wherein:
the first rows and the second rows are alternatingly arranged.
7. The sensor unit of claim 1 , wherein:
the connection positions of the first imaging pixels are off-center with respect to the associated charge collection electrodes.
8. The sensor unit of claim 1 , wherein:
the connection positions of the second imaging pixels are off-center with respect to the associated charge collection electrodes.
9. The sensor unit of claim 1 , wherein:
the second imaging pixels are shifted less than a width of the imaging pixels from a position where the second imaging pixels are aligned with the first imaging pixels.
10. The sensor unit of claim 1 , wherein:
the second imaging pixels are shifted half a width of the imaging pixels from a position where the second imaging pixels are aligned with the first imaging pixels.
11. The sensor unit of claim 1 , wherein:
each readout pixel comprises readout pixel electronics with at least one electronic component specific for an associated readout pixel.
12. The sensor unit of claim 11 , wherein:
the at least one electronic component comprises an amplifier, a comparator and/or a counter for counting photon pulses.
13. The sensor unit of claim 1 , wherein:
each interconnection comprises a solder bump.
14. The sensor unit of claim 1 , wherein:
the conversion element comprises a semiconductor substrate, such as a cadmium telluride (CdTe) or a cadmium zinc telluride (CdZnTe or CZT) substrate.
15. The sensor unit of claim 1 , wherein:
each imaging pixel is configured to directly convert ionizing radiation into an electrical charge.
16. A method of using a sensor unit for a radiation detector, the method comprising:
providing a sensor unit comprising:
a conversion element comprising a plurality of imaging pixels, each imaging pixel being configured to directly convert radiation into an electrical charge, each imaging pixel comprising a charge collection electrode, and the imaging pixels comprising first imaging pixels and second imaging pixels; and
a readout substrate comprising a plurality of readout pixels arranged in a grid, each readout pixel being connected to an associated imaging pixel by means of an interconnection at a connection position on the charge collection electrode;
wherein the second imaging pixels are shifted in a shifting direction relative to the first imaging pixels; and
wherein the connection positions in relation to the charge collection electrodes are different between the first imaging pixels and the second imaging pixels;
moving the sensor unit in a scanning direction substantially perpendicular to the shifting direction;
generating electric signals responsive to radiation onto the imaging pixels; and
sampling the electric signals at successive increments of movement of the sensor unit in the scanning direction equal to or less than a length of each imaging pixel in the scanning direction.
17. The method according to claim 16 , further comprising:
generating an image from super resolution pixels, wherein each super resolution pixel is derived from at least two successive imaging pixels in the scanning direction with a super resolution pixel width that is less than 75% of an imaging pixel width.
18. The method according to claim 17 , wherein each super resolution pixel is configured to generate radiation energy values different from a neighboring super resolution pixel and the number of super resolution pixel is at least 50% greater than the number of imaging pixels in the shifting direction.
19. A sensor unit for a radiation detector, the sensor unit comprising:
a plurality of means for directly converting radiation into an electrical charge divided into a plurality of first means for directly converting radiation into an electrical charge and a plurality of second means for directly converting radiation into an electrical charge, each means for directly converting radiation into an electrical charge including means for collecting charge;
a plurality of means for reading out an electrical signal from an associated one of the means for directly converting radiation into an electrical charge; and
a plurality of means for interconnecting each of the means for reading out an electrical signal to a connection position of the means for collecting charge of the associated one of the means for directly converting radiation into an electrical charge;
wherein the second means for directly converting radiation into an electrical charge are shifted in a shifting direction relative to the first means for directly converting radiation into an electrical charge; and
wherein the connection positions of the means for collecting charge are different between the first means for directly converting radiation into an electrical charge and the second means for directly converting radiation into an electrical charge.
20. The sensor unit of claim 19 , further comprising:
means for generating an image from at least two successive means for directly converting radiation into an electrical charge in the scanning direction with a width of the means for generating an image that is less than 75% of a width of means for directly converting radiation into an electrical charge width.
21. The sensor unit of claim 20 , further comprising:
means for generating radiation energy values different from a neighboring means for generating an image and the number of means for generating an image is at least 50% greater than the number of the means for directly converting radiation into an electrical charge in the shifting direction.