Image-pickup system and method of controlling same

• US 8,648,947 B2
• Filed: 11/15/2011
• Issued: 02/11/2014
• Est. Priority Date: 11/22/2010
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sato, Sho, Endo, Tadao, Kameshima, Toshio, Yagi, Tomoyuki, Takenaka, Katsuro, Iwashita, Atsushi
• Primary Examiner(s): CHEN, CHIA WEI A
• Application Number:
  US13/296,468
• Publication Number:
  US 20120127353A1
• Time in Patent Office: 819 Days
• Field of Search: 348302-310, 348362-368, 348/370, 348/371, 250/200, 250/206, 257/53, 257215-234
• US Class Current: 348/302
• CPC Class Codes: G01T 1/17 Circuit arrangements not adapted to a particular type of detector pulse-selection circuits H03K, G01R
• CPC Class Codes: G01T 1/208 Circuits specially adapted for scintillation detectors, e.g. for the photo-multiplier section
• CPC Class Codes: H04N 25/30 for transforming X-rays into image signals
• CPC Class Codes: H04N 25/621 for the control of blooming
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

An image-pickup apparatus including a detector comprising a detecting unit and a reading circuit, the detecting unit including pixels, each of which including a conversion element, the reading circuit which includes a connecting unit that is electrically connected to a signal wire transferring an electric signal and that electrically connects the signal wire to a node, and which performs a reading operation to output the electric signal from the pixel. A control unit controls an operation of the reading circuit, and a sensing unit senses the end of radiation irradiation based on an output of the reading circuit, which is acquired during the period of an accumulation operation of the detector. The control unit starts establishing the electrical connection between the signal wire and the node through the connecting unit based on the sensed irradiation end, and retains the electrical connection until the start of the reading operation.

Claims

1. An image-pickup system comprising:

an image-pickup apparatus including a detector comprising a detecting unit and a reading circuit, the detecting unit being provided with pixels that are arranged in matrix-form, where each of the pixels includes a conversion element converting a radiation into an electric charge, the reading circuit including a connecting unit that is electrically connected to a signal wire transferring an electric signal corresponding to the electric charge and that electrically connects the signal wire to a node to which a specified potential is supplied, the reading circuit being provided to perform a reading operation to output the electric signal from the pixel, and a control unit configured to control an operation of the reading circuit; and

a sensing unit configured to sense an end of irradiation of a radiation based on an output of the reading circuit, the output being acquired during a time period where the detector performs an accumulation operation,

wherein the control unit controls the reading circuit so that the connecting unit starts establishing the electrical connection between the signal wire and the node based on the sensed end of the irradiation, and retains the electrical connection until the start of the reading operation.

2. The image-pickup system according to claim 1, wherein the control unit controls the reading circuit so that the reading circuit acquires an output signal or an output-data item of the reading circuit at a specified frequency during a time period where the radiation irradiation is performed.

3. The image-pickup system according to claim 1, wherein the sensing unit makes a comparison between a plurality of the output signals or the output-data items that are acquired consecutively.

4. The image-pickup system according to claim 1, wherein the pixel further includes a switching element outputting an electric signal corresponding to the electric charge,

wherein a plurality of the signal wires is electrically connected to a plurality of the switching elements that are arranged in a column direction, and is arranged in a row direction,

wherein the reading circuit further includes a plurality of amplifying circuits that are provided for a plurality of the signal wires, where each of the amplifying circuits includes an integrating amplifier having a reset switch and a sample-and-hold circuit which samples and temporarily holds an output signal of the integrating amplifier, and a multiplexer outputting electric signals that are read in parallel from the amplifier circuits in sequence as serial image signals, and

wherein the connecting unit includes the reset switches.

5. The image-pickup system according to claim 4, wherein the sample-and-hold circuit includes a signal sample-and-hold circuit that samples and temporarily holds an image signal, and a noise sample-and-hold circuit that samples and temporarily holds a noise component of the integrating amplifier, and

wherein the control unit controls the reading circuit so that the electrical connection between the signal wire and the node, the electrical connection being established by the reset switch, is retained from the end of the irradiation to the start of the noise-component sampling performed by the noise sample-and-hold circuit based on the sensed end of the irradiation.

6. The image-pickup system according to claim 5, wherein the signal sample-and-hold circuit is provided for each of an odd row and an even row, and the noise sample-and-hold circuit is provided for each of an odd row and an even row.

7. The image-pickup system according to claim 4, wherein, in the image-pickup apparatus, a plurality of driving wires which is electrically connected to the switching elements that are arranged in the row direction is arranged in the column direction,

wherein the image-pickup apparatus further includes a driving circuit driving the detecting unit by supplying a conducting voltage or a non-conducting voltage of the switching element to the driving wires in rows, and

wherein the control unit controls the reading circuit and the driving circuit to retain the electrical connection between the signal wire and the node, the electrical connection being established by the reset switch, from the end of the irradiation until the start of the driving of the detecting unit, the driving being performed by the driving circuit, based on the sensed end of the irradiation.

8. The image-pickup system according to claim 1, wherein the pixels of the detecting unit are divided into a plurality of pixel groups, and

wherein the reading circuit includes a plurality of reading-circuit units, and one of the reading-circuit units corresponds to one of the pixel groups and electric signals that are transmitted from the pixel groups are output in parallel by the reading-circuit units.

9. The image-pickup system according to claim 1, wherein the conversion element includes a photoelectric conversion element converting light into the electric charge and a wavelength converter converting a radiation into the light falling within a band of wavelengths that can be sensed by the photoelectric conversion element, or directly converts a radiation into the electric charge.

10. The image-pickup system according to claim 1, further comprising:

a radiation generator configured to irradiate the image-pickup apparatus with a radiation; and

a control apparatus configured to control the image-pickup apparatus and the radiation generator.

11. A method of controlling an image-pickup system including an image-pickup apparatus including a detector comprising a detecting unit and a reading circuit, the detecting unit being provided with pixels that are arranged in matrix-form, where each of the pixels includes a conversion element converting a radiation into an electric charge, the reading circuit including a connecting unit that is electrically connected to a signal wire transferring an electric signal corresponding to the electric charge and that electrically connects the signal wire to a node to which a specified potential is supplied, the reading circuit being provided to perform a reading operation to output the electric signal from the pixel, and a control unit configured to control an operation of the reading circuit, the method comprising the steps of:

sensing an end of radiation irradiation based on an output of the reading circuit, the output being acquired during a time period where the detector performs an accumulation operation, and

starting establishing the electrical connection between the signal wire and the node by the connecting unit based on the sensed end of the irradiation and retaining the electrical connection by the connecting unit until the start of the reading operation.

12. A non-transitory computer-readable storage medium storing thereon a computer-executable program which when executed on a computer causes the computer to control an image-pickup system, the image pickup system including a radiation image-pickup apparatus including a detector comprising a detecting unit and a reading circuit, the detecting unit being provided with pixels that are arranged in matrix-form, where each of the pixels includes a conversion element converting a radiation into an electric charge, the reading circuit including a connecting unit that is electrically connected to a signal wire transferring an electric signal corresponding to the electric charge and that electrically connects the signal wire to a node to which a specified potential is supplied, the reading circuit being provided to perform a reading operation to output the electric signal from the pixel, and a control unit configured to control an operation of the reading circuit, the program causing the computer to execute the steps of:

sensing an end of radiation irradiation based on an output of the reading circuit, the output being acquired during a time period where the detector performs an accumulation operation, and starting establishing the electrical connection between the signal wire and the node by the connecting unit based on the sensed end of the irradiation and retaining the electrical connection by the connecting unit until the start of the reading operation.