US 6,476,867 B1Granted

Photoelectric conversion apparatus, driving method and x-ray image pickup apparatus using the same

AssigneeCanon Kabushiki Kaisha

InventorsIsao Kobayashi, Noriyuki Kaifu, Shinichi Takeda, Masakazu Morishita, Tadao Endo

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Abstract

In order to realize a photoelectric conversion apparatus capable of easily switching a mode requiring a wide dynamic range in obtaining a motion image and a mode requiring a reduction in noise in obtaining a still image, a mode switching means is used, when a refresh operation is performed for each photoelectric conversion element, to switch between a mode of setting the potential of one electrode of the photoelectric conversion element to be higher than the potential of the other electrode, and a mode of setting the potential of one electrode of the photoelectric conversion element to be lower than the potential of the other electrode, thereby arbitrarily changing the refresh voltage. With this operation, desired photoelectric conversion signals for a motion image and a still image can be obtained.

Claims38

Dependent claims

A driving method for a photoelectric conversion apparatus comprising:

a photoelectric conversion element having first and second electrodes;
and
mode switching means for performing a refresh operation for said photoelectric conversion element by switching between a first refresh mode of setting a potential of said first electrode to be higher than a potential of said second electrode, and a second refresh mode of setting the potential of said first electrode to be lower than the potential of said second electrode, wherein said photoelectric conversion element is formed by depositing, on an insulating substrate, a first electrode layer, a first insulating layer for inhibiting passage of carriers of a first type and carriers of a second type having a polarity opposite to that of the carriers of the first type, a photoelectric conversion semiconductor layer, an injection inhibiting layer for inhibiting the carriers of the first type from being injected into the semiconductor layer, and a second layer,
said apparatus further comprising refresh mode operation means operating in the first refresh mode of applying an electric field to each layer to set
(VrGq)<(VD−VFB)q (1)
where VrG is the voltage of the first electrode layer of said photoelectric conversion element, q is the charge of a carrier of the first type, VD is the voltage of the second electrode layer, and VFB is a threshold voltage, and operating in the second refresh mode of applying an electric field to set
(VrGq)≧(VD−VFB)q (2),
said mode switching means switching between the first and second refresh modes and causing said apparatus to operate in one of the modes, wherein switching is performed to set the first refresh mode of applying an electric field to each layer to set
(VrGq)<(VD−VFB)q (1)
when a still image is to be obtained, and switching is performed to set the second refresh mode of applying an electric field to set
(VrGq)≧(VD−VFB)q (2)
when a moving image is to be obtained.

9 more elements

A photoelectric conversion apparatus comprising:

a photoelectric conversion element having first and second electrodes;
and
mode switching means for performing a refresh operation for said photoelectric conversion element by switching between a first refresh mode of setting a potential of said first electrode to be higher than a potential of said second electrode, and a second refresh mode of setting the potential of said first electrode to be lower than the potential of said second electrode, wherein the first refresh mode is set when a still image is obtained and the second refresh mode is set when a moving image is obtained.

A photoelectric conversion apparatus comprising:

a photoelectric conversion element having a pair of electrodes and having a semiconductor layer and an injection inhibiting layer between said pair of electrodes;
and
a circuit for applying a sensing voltage between said pair of electrodes to effect a sensing of said photoelectric conversion element;
a refresh circuit for applying a refresh voltage between said pair of electrodes for refreshing said photoelectric conversion element,
wherein said refresh circuit comprises a switch for alternatively selecting either application of a refresh voltage of a first polarity between said pair of electrodes, or application of a refresh voltage of a second polarity, opposite to said first polarity between said pair of electrodes,
wherein said switch is turned on in changing between still image reading and moving image reading.

3 more elements

A photoelectric conversion apparatus comprising:

a photoelectric conversion element having a pair of electrodes and having a semiconductor layer and an injection inhibiting layer between said pair of electrodes;
a circuit for applying a sensing voltage between said pair of electrodes to effect a sensing of said photoelectric conversion element;
and
a refresh circuit for applying a refresh voltage between said pair of electrodes for refreshing said photoelectric conversion element,
wherein said refresh circuit comprises a switch for alternatively selecting either application of
(i) a first refresh voltage between said pair of electrodes, said first refresh voltage satisfying the following equation (1):
VrG<VD−VFB (1)
where:
VrG is the voltage of a first electrode of said pair of electrodes,
VD is the voltage of a second electrode of said pair of electrodes, and
VFB is a threshold voltage, or
(ii) application of a second refresh voltage between said pair of electrodes, said second refresh voltage satisfying the following equation (2):
VrG≧VD−VFB (2)
wherein said switch is turned on when changing between still image reading and moving image reading.

11 more elements

Dependencies are inferred from the claim text.