Detecting apparatus and detecting system
A detecting apparatus formed on a substrate, includes a plurality of pixels arranged in a matrix, and a signal line electrically connected to the pixels. Each of the pixels includes a sensing element that converts radiant ray or light to electric charges, an amplification thin film transistor that outputs an electric signal based on an amount of the electric charges, a capacitor that holds an electric signal output by the amplification thin film transistor, and a transfer thin film transistor that transfers an electric signal held in the capacitor to the signal line.
1. A detecting apparatus formed on a substrate, the detecting apparatus comprising:
a plurality of pixels arranged in a matrix; and
a signal line electrically connected to the pixels, wherein
each of the pixels includes:
a sensing element that converts radiant ray or light to electric charges,
an amplification thin film transistor that outputs an electric signal based on an amount of the electric charges,
a capacitor that holds an electric signal output by the amplification thin film transistor, and
a transfer thin film transistor that transfers an electric signal held in the capacitor to the signal line.
2. The detecting apparatus according to claim 1 , wherein the capacitor is placed between the amplification thin film transistor and the transfer thin film transistor and the substrate.
3. The detecting apparatus according to claim 1 , wherein a capacitance of the capacitor is 3 to 10 times of a capacitance of the sensing element and is 1/30to 1/10 of the parasitic capacitance of the signal line.
4. The detecting apparatus according to claim 1 , wherein the amplification thin film transistor and the transfer thin film transistor are thin film transistors of polycrystalline silicon,
the capacitor includes a first conductive layer placed on the substrate, an insulating layer placed on the first conductive layer, and a second conductive layer placed on the insulating layer, and
the insulating layer contains silicon nitride.
5. The detecting apparatus according to claim 4 , further comprising a passivation layer and an interlayer insulating layer placed between the amplification thin film transistor and the transfer thin film transistor and the capacitor, wherein the passivation layer and the interlayer insulating layer contain silicon nitride, and the interlayer insulating layer is thicker than the insulating layer.
6. The detecting apparatus according to claim 5 , wherein the thickness of the interlayer insulating layer is 6 to 20 times of the thickness of the insulating layer.
7. The detecting apparatus according to claim 4 , further comprising:
an electrode power supply line electrically connected to one electrode of the sensing element;
an operating power line electrically connected to one of a source and a drain of the amplification thin film transistor; and
a transfer drive line connected to a gate of the transfer thin film transistor, wherein
the amplification thin film transistor has a gate electrically connected to another electrode of the sensing element,
the first conductive layer is electrically connected to another one of a source and drain of the amplification thin film transistor, and the second conductive layer is electrically connected to one of a source and a drain of the transfer thin film transistor, and
another one of source and drain of the transfer thin film transistor is electrically connected to the signal line.
8. The detecting apparatus according to claim 7 , wherein
each of the pixels further includes a reset thin film transistor that resets a gate of the amplification thin film transistor, a selection thin film transistor that selects the pixel, and a capacitance reset thin film transistor that resets the capacitor,
the reset thin film transistor has one of a source and a drain electrically connected to a reset power supply line, and another one of a source and drain electrically connected to a gate of the amplification thin film transistor,
the selection thin film transistor has one of a source and a drain electrically connected to the another one of the source and drain of the amplification thin film transistor, and the another one of the source and drain of the selection thin film transistor is electrically connected to the first conductive layer, and
the capacitance reset thin film transistor has one of a source and a drain electrically connected to a line to which a predetermined potential may be supplied, and the capacitance reset thin film transistor has another one of a source and drain electrically connected to the first conductive layer.
9. The detecting apparatus according to claim 8 , wherein the first conductive layer and the second conductive layer contain an optical transparent conductive material.
10. The detecting apparatus according to claim 8 , further comprising:
a selection drive line electrically connected to a gate of the selection thin film transistor;
a reset drive line electrically connected to a gate of the reset thin film transistor;
a drive circuit electrically connected to the transfer drive line and the selection drive line; and
a readout circuit electrically connected to the signal line; and
a control circuit that controls the drive circuit and the readout circuit, wherein
the readout circuit includes a reset switch that resets the signal line, an operational amplifier electrically connected to the signal line, and a sample hold circuit electrically connected to the operational amplifier;
the sample hold circuit includes a signal sample hold circuit and a noise sample hold circuit; and
the control circuit controls the drive circuit and the readout circuit such that the noise sample hold circuit may hold an output of the operational amplifier when the transfer thin film transistor has a conduction state after the signal line is reset by the reset switch, and the signal sample hold circuit may hold an output of the operational amplifier after the transfer thin film transistor is brought into conduction and the transfer thin film transistor is brought into conduction after the noise sample hold circuit holds an output of the operational amplifier.
11. The detecting apparatus according to claim 10 , wherein the capacitance reset thin film transistor has a gate electrically connected to the selection drive line.
12. The detecting apparatus according to claim 4 , further comprising:
an electrode power supply line electrically connected to one electrode of the sensing element;
an operating power line electrically connected to one of a source and a drain of the amplification thin film transistor; and
a transfer drive line connected to a gate of the transfer thin film transistor, wherein
the amplification thin film transistor has a gate electrically connected to another electrode of the sensing element,
the first conductive layer is electrically connected to the another one of the source and drain of the amplification thin film transistor and one of a source and a drain of the transfer thin film transistor,
the second conductive layer is electrically connected to a line to which a predetermined potential may be supplied, and
the another one of the source and drain of the transfer thin film transistor is electrically connected to the signal line.
13. The detecting apparatus according to claim 12 , further comprising a power supply circuit electrically connected to the line to which a predetermined potential may be supplied, and the power supply circuit is configured to change the potential to be supplied to the line to which a predetermined potential may be supplied.
14. The detecting apparatus according to claim 12 , wherein
each of the pixels further includes a reset thin film transistor that resets a gate of the amplification thin film transistor, a selection thin film transistor that selects the pixel, and a capacitance reset thin film transistor that resets the capacitor,
the reset thin film transistor has one of a source and a drain electrically connected to a reset power supply line, and another one of a source and drain is electrically connected to a gate of the amplification thin film transistor,
selection thin film transistor has one of a source and a drain electrically connected to the another one of the source and drain of the amplification thin film transistor, and the selection thin film transistor has the another one of the source and drain electrically connected to the first conductive layer,
the capacitance reset thin film transistor has one of a source and a drain electrically connected to a line to which a predetermined potential may be supplied, and
the capacitance reset thin film transistor has another one of a source and drain electrically connected to the first conductive layer.
15. The detecting apparatus according to claim 14 , wherein the first conductive layer and the second conductive layer contain an optical transparent conductive material.
16. The detecting apparatus according to claim 14 , further comprising:
a selection drive line electrically connected to a gate of the selection thin film transistor;
a reset drive line electrically connected to a gate of the reset thin film transistor;
a drive circuit electrically connected to the transfer drive line and the selection drive line;
a readout circuit electrically connected to the signal line; and
a control circuit that controls the drive circuit and the readout circuit, wherein
the readout circuit includes a reset switch that resets the signal line, an operational amplifier electrically connected to the signal line, and a sample hold circuit electrically connected to the operational amplifier,
the sample hold circuit includes a signal sample hold circuit and a noise sample hold circuit, and
the control circuit controls the drive circuit and the readout circuit such that the noise sample hold circuit may hold an output of the operational amplifier when the transfer thin film transistor has a conduction state after the signal line is reset by the reset switch and the signal sample hold circuit may hold an output of the operational amplifier after the transfer thin film transistor is brought into conduction and the transfer thin film transistor is brought into conduction after the noise sample hold circuit holds an output of the operational amplifier.
17. The detecting apparatus according to claim 16 , wherein the capacitance reset thin film transistor has a gate electrically connected to the selection drive line.
18. A detecting system comprising:
the detecting apparatus according to claim 1 ;
a signal processing unit that processes a signal from the detecting apparatus;
a display unit that displays a signal from the signal processing unit; and
a transmission processing unit configured to transmit a signal from the signal processing unit.