Radiation image capturing apparatus and method of driving the same

Patent metadata

Field	Value
Publication number	US-9445030-B2
Application number	US-201514801549-A
Country	US
Kind code	B2
Filing date	Jul 16, 2015
Priority date	Jul 18, 2014
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

A radiation image capturing apparatus, comprising a sensor configured to monitor an irradiating dose of radiation, a switch configured output a sensor signal from the sensor, a readout unit configured to read out the sensor signal via a signal line, and a controlling unit, wherein the controlling unit performs first control of repeatedly performing, while the sensor is irradiated, a series of operations including a first operation of setting the switch to a conductive state and a second operation of setting the switch to a non-conductive state, second control of reading out the sensor signal in the first operation as a first signal and a potential of the signal line in the second operation as a second signal, and third control of calculating the irradiating dose of radiation based on the first signal and the second signal.

First claim

What is claimed is:

1. A radiation image capturing apparatus, comprising:
a sensor configured to monitor an irradiating dose of radiation from a radiation source;
a switch configured to cause said sensor to output a sensor signal upon changing from a non-conductive state to a conductive state;
a readout unit configured to read out the sensor signal from said sensor via said switch and a signal line; and
a controlling unit configured to control the switch and the readout unit so as to perform first control of repeatedly performing, while radiation from the radiation source irradiates said sensor, a series of operations including a first operation of setting said switch to the conductive state and a second operation of setting said switch to the non-conductive state,
second control of reading out, by said readout unit, the sensor signal from said sensor in the first operation as a first signal and reading out, by said readout unit, a potential of the signal line in the second operation as a second signal, and
third control of calculating the irradiating dose of radiation based on the first signal and the second signal.

2. The apparatus according to claim 1 , wherein in the third control, said controlling unit outputs a control signal for controlling the radiation source and at least one of the irradiation dose, an irradiation intensity, and an irradiation time of radiation.

3. The apparatus according to claim 1 , wherein for each of the series of the operations performed repeatedly, said controlling unit calculates a difference between the first signal obtained in the first operation and the second signal obtained in the second operation, and performs the third control based on the difference if the difference satisfies a predetermined condition.

4. The apparatus according to claim 1 , wherein said controlling unit calculates an average value of a difference between the first signal obtained by the first operation and the second signal obtained by the second operation for the series of operations performed not less than twice, and performs the third control based on the average value.

5. The apparatus according to claim 1 , wherein for each of the series of the operations performed repeatedly, said controlling unit performs the third control based on a difference between the first signal obtained by the first operation and the second signal obtained by the second operation and if the difference does not satisfy a predetermined condition, said controlling unit performs the third control based on an average value of differences between the first signals obtained by the first operations and the second signals obtained by the second operations for the series of operations performed not less than twice.

6. The apparatus according to claim 1 , wherein said controlling unit performs fourth control of setting each switch to the conductive state and initializing each sensor before radiation irradiation starts, and
said controlling unit
performs the first control, the second control, and the third control after a predetermined time elapses since the fourth control has ended, or
performs the first control and the second control since the fourth control has ended and performs, after the predetermined time has elapsed since the fourth control had ended, the third control on the first control and the second control that have been performed after the predetermined time had elapsed.

7. The apparatus according to claim 6 , further comprising a detecting unit configured to detect that the radiation source has started radiation irradiation,
wherein said controlling unit terminates the fourth control based on detection by said detecting unit.

8. The apparatus according to claim 6 , further comprising a memory configured to hold a reference table for specifying the predetermined time,
wherein said controlling unit sets, while referring to the reference table, the predetermined time based on an imaging condition set by a user.

9. The apparatus according to claim 1 , further comprising a plurality of pixels configured to obtain image data corresponding to radiation,
wherein at least one of the plurality of pixels includes said sensor and said switch.

10. A method of driving a radiation image capturing apparatus,
the radiation image capturing apparatus including
a sensor configured to monitor an irradiating dose of radiation from a radiation source,
a switch configured to cause the sensor to output a sensor signal upon changing from a non-conductive state to a conductive state, and
a readout unit configured to read out the sensor signal from the sensor via the switch and a signal line,
the method comprising steps of:
repeatedly performing, while radiation from the radiation source irradiates the sensor, a series of operations including a first operation of setting the switch to the conductive state and a second operation of setting the switch to the non-conductive state;
reading out, by the readout unit, the sensor signal from the sensor in the first operation as a first signal and reading out, by the readout unit, a potential of the signal line in the second operation as a second signal; and
calculating the irradiating dose of radiation based on the first signal and the second signal.

11. A radiation image capturing apparatus, comprising:
a sensor configured to monitor an irradiating dose of radiation from a radiation source;
a switch for outputting a signal from said sensor;
a controlling unit configured to control the switch so as to perform, while radiation from the radiation source irradiates said sensor, a first operation of switching said switch to a conductive state and a second operation of switching said switch to a non-conductive state; and
a calculation unit configured to calculate the irradiating dose of radiation based on a first signal obtained corresponding to the first operation and a second signal obtained corresponding to the second operation.

12. The apparatus according to claim 11 , wherein said controlling unit outputs a control signal for controlling the radiation source and at least one of the irradiation dose, an irradiation intensity, and an irradiation time of radiation.

13. The apparatus according to claim 11 , wherein
said controlling unit, while the radiation from the radiation source irradiates said sensor, repeatedly performs a series of operations including the first operation and the second operation, and
said calculation unit calculates, for each of the series of the operations performed repeatedly, the irradiating dose of radiation based on a difference between the first signal and the second signal.

14. The apparatus according to claim 11 , wherein
said controlling unit, while the radiation from the radiation source irradiates said sensor, repeatedly performs a series of operations including the first operation and the second operation, and
said calculation unit calculates the irradiating dose of radiation based on an average value of a difference between the first signal and the second signal for the series of operations performed not less than twice.

15. The apparatus according to claim 11 , wherein
said controlling unit, while the radiation from the radiation source irradiates said sensor, repeatedly performs a series of operations including the first operation and the second operation, and
said calculation unit calculates, for each of the series of the operations performed repeatedly, the irradiating dose of radiation based on a difference between the first signal and the second signal and if the difference does not satisfy a predetermined condition, said calculation

Assignees

• Canon Kk

Inventors

• Yagi Tomoyuki
• Kameshima Toshio
• Takenaka Katsuro
• Iwashita Atsushi
• Sato Eriko
• Okada Hideyuki
• Ryu Takuya
• Terui Kosuke

Classifications

• H04N25/75 Primary

  Circuitry for providing, modifying or processing image signals from the pixel array · CPC title

• H04N25/78

  Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters · CPC title

• H04N5/33

  Transforming infrared radiation (cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20) · CPC title

• H04N5/378 Primary

  Electricity · mapped topic