Solid state image sensing device

• US 20080018766A1
• Filed: 07/17/2007
• Published: 01/24/2008
• Est. Priority Date: 07/18/2006
• Status: Active Grant

• Current Assignee: Sony Semiconductor Solutions Corporation (Sony Group Corp.)
• Original Assignee: Konica Minolta Holdings Incorporated (Konica Minolta Inc.)
• Inventors: Miyatake, Shigehiro
• Granted Patent: US 7,663,683 B2
• Time in Patent Office: Days
• US Class Current: 348/308
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/573 the logarithmic type
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion
• CPC Class Codes: H04N 3/155 Control of the image-sensor operation, e.g. image processing within the image-sensor

Abstract

A solid state image sensing device comprises an MOS transistor T2 that has a source thereof connected to a drain of an MOS transistor T1 being provided with a transfer gate which is connected to an embedded photodiode PD; an MOS transistor T5 that has a gate thereof connected to the drain of the MOS transistor T1; and a condenser that has a source thereof connected to the MOS transistor T5. When a linear conversion operation is performed in an entire refuge of luminance, the MOS transistor T2 works, serving as a switch for resetting, and at least when a logarithmic conversion operation is performed in a part of the range of luminance, the MOS Transistor T2 works in a sub-threshold region.

Claims

1. A solid state image sensing device comprising:

a plurality of pixels comprising;

a photoelectric conversion element that generates a photo-charge in accordance with an amount of an incident light and stores a generated photo-charge therein;

a charge-holding portion that has a photo-charge transferred from the photoelectric conversion element so as to hold it temporarily;

a transfer gate that is formed between the photoelectric conversion element and the charge-holding portion;

a first transistor that has a first electrode thereof connected to the charge-holding portion, has a second electrode thereof applied with a direct current voltage, and has a control electrode thereof provided with a first control signal that can change over among three voltage levels;

a second transistor that is provided with a first electrode, a second electrode and a control electrode and has a control electrode thereof connected to the charge-holding portion;

a third transistor that has a second electrode thereof connected to a first electrode of the second transistor, has a first electrode thereof applied with a direct current voltage, and has a control electrode thereof provided with a second control signal that can change over among three voltage levels;

a capacitative element that has one end thereof connected to a first electrode of the second transistor;

wherein, a first state is a state in which by setting the second control signal to be at an intermediate voltage level, thereby employing the third transistor as a constant current load, an electric signal which changes in a linear manner in accordance with an integration value of an amount of incident light in an entire range of luminance is outputted from the pixel; and

a second state is a state in which by setting the first control signal to be at an intermediate voltage level, thereby operating the first and the second transistors in a sub-threshold region, an electric signal which changes in a natural logarithmic manner in accordance with an integration value of an amount of incident light at least in a part of a range of luminance is outputted from the pixel.

2. A solid state image sensing device as descried in claim 1:

wherein, when an image sensing operation is performed in the first state, the first transistor is employed as a transistor for resetting the charge-holding portion so as have the first control signal serve as a signal having two voltage levels without using an intermediate voltage level among three voltage levels.; and

when an image sensing operation is performed in the second state, the third transistor is employed as a transistor for resetting the compatitative element so as to have the second control signal serve as a signal having two voltage levels without using an intermediate voltage level among three voltage levels.

3. A solid state image sensing device as described in claim 1, further comprising:

an output signal line that is connected to the pixel and has an electric signal outputted from the pixel; and

the pixel further comprising;

an amplification portion that amplifies an electric signal appearing to the capacitative element; and

a reading-out switch that is connected to the output signal line and outputs an electric signal being amplified in the amplification portion to the output signal line.

4. A solid state image sensing device as described in claim 1:

wherein, the image sensing operation for each frame is selected and changed over between the first state and the second state.