Photoelectric converting apparatus

A technology of photoelectric conversion and photoelectric conversion elements, applied in the direction of TV, electrical components, color TV, etc., can solve the problems of difficult to form high-sensitivity photoelectric conversion equipment, output voltage loss, high power consumption, etc., to reduce the influence of resistance , low power consumption, low heat effect

Inactive Publication Date: 2009-01-14
CANON KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] Then, existing photoelectric conversion devices such as radiation image pickup devices cannot be constructed as large-area sensors due to such a significant loss in output voltage.
In addition, due to such a significant loss of output voltage, this device is susceptible to noise generated in the amplifier of the readout circuit and external noise, and thus, it is difficult to constitute a highly sensitive photoelectric conversion device
The influence of such noise can be reduced by supplying a constant current power supply or a low-noise amplifier to the readout circuit, however, such a low-noise amplifier as a special circuit causes disadvantages such as an increase in cost
Also, since such LNAs typically have high electrical power consumption, the readout circuitry causes non-negligible heating

Method used

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Examples

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no. 1 example

[0040] First, a first embodiment of the present invention will be described. FIG. 1 is a circuit diagram showing a circuit configuration of a photoelectric conversion device constituting a first embodiment of the present invention, particularly an X-ray image pickup device.

[0041]In this embodiment, the sensor array 1 is formed on the glass substrate 2 by arranging four pixels PE11, PE12, PE21, and PE22 in two rows and two columns, but the number of pixels constituting the sensor array 1 is not limited to such example. Each pixel has a photoelectric conversion element PD composed of a PIN photodiode formed of amorphous silicon, and a storage capacitor Cs that accumulates signal charges generated by the photoelectric conversion element PD. The photoelectric conversion element PD and the storage capacitor Cs are grounded at one end thereof and interconnected at the other end thereof. Each pixel also has a reset MOS transistor RT, a selection MOS transistor ST, and a source f...

no. 2 example

[0053] Next, a second embodiment of the present invention will be described. 3 is a circuit diagram of a circuit configuration of a photoelectric conversion device, particularly an X-ray image pickup device, constituting a second embodiment of the present invention. In the second embodiment, instead of the constant current source I employed in the first embodiment, a thin film transistor (TFT) CT formed of amorphous silicon is provided. The gate of the thin film transistor CT receives a voltage from a power source 7 for a constant current source. Such a structure can be produced by a simple manufacturing process, because a constant current source can be formed simultaneously with other transistors (reset, select, and source follower) by film formation. Thin film transistors respectively used for reset, selection, source follower, and constant current source may have the same laminated film thickness or different film thicknesses. They may also have a common doping state (n-t...

no. 3 example

[0059] A third embodiment of the present invention will be described below. 5 is a circuit diagram of a circuit configuration of a photoelectric conversion device, particularly an X-ray image pickup device, constituting a third embodiment of the present invention. Contrary to the second embodiment in which the thin film transistor CT constituting the constant current source is placed between the pixel and the readout circuit 3, in the third embodiment, on the common signal line, the thin film transistor CT is located at a distance from the pixel compared with the pixel. The readout circuit 3 is farther away. In other words, the pixel is arranged between the thin film transistor CT and the readout circuit 3 .

[0060] The advantage of arranging the constant current source at a distance from the readout circuit will now be described with reference to FIGS. 15, 16 and 17. FIG. FIG. 15 shows a structure in which, for each signal line, a constant current source is spaced apart fr...

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Abstract

A photoelectric converting apparatus of the present invention includes a photoelectric converting element, a resetting transistor in which a source is connected to the photoelectric converting element and a drain is connected to a resetting power source, a readout transistor in which a gate is connected to the photoelectric converting element and a drain is connected to a readout power source, a signal line connected to a source of the readout transistor, a selecting transistor connected between the readout power source or the signal line and the readout transistor, and a constant current source connected to the signal line.

Description

technical field [0001] The present invention relates to a photoelectric conversion device such as a radiation coil image pickup device, and in particular, to a photoelectric conversion device designed to reduce sensitivity drop caused by parasitic capacitance. Background technique [0002] A photoelectric conversion device, such as a radiation image pickup device, that reads charges obtained by photoelectric conversion in photoelectric conversion elements of a sensor array using amorphous silicon or polysilicon by transfer to capacitance by matrix driving, has been proposed Know. [0003] FIG. 9 is a schematic circuit diagram showing a conventional photoelectric conversion device (radiation image pickup device). In an existing photoelectric conversion device, as shown in FIG. 9 , pixels indicated by dotted boxes include PIN photodiodes PD and selection thin film transistors (TFTs) ST, and such pixels are arranged two-dimensionally, thereby constituting the sensor array 101 ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N5/335H04N5/32H01L27/146
Inventor 龟岛登志男
Owner CANON KK
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