SOLID-STATE IMAGING APPARATUS AND METHOD FOR DRIVING THE SAME

Abstract

To provide a solid-state imaging apparatus which is capable of preventing electric charge from being injected from a semiconductor substrate while electric charge is being accumulated into photodiodes. The solid-state imaging apparatus includes a solid-state imaging device and a driving pulse control unit. The solid-state imaging device includes: a semiconductor substrate, photodiodes which are two-dimensionally formed on the semiconductor substrate, and vertical Charge-coupled devices (CCDs) having at least one arranged read-out gate and non-read-out gate for each of the photodiodes, the read-out gate being for reading out accumulated electric charge from the associated photodiode, and the non-read-out gate being not for reading out accumulated electric charge from the associated photodiode. The driving pulse control unit applies driving pulses sequentially to the respective read-out gates in order to change the read-out gates from stand-by LOW-voltage states to MIDDLE-voltage states, and apply a driving pulse for maintaining a LOW-voltage state of at least one of non-read-out gates adjacent to a last read-out gate in the order of the change among the non-read-out gates, during the change starting with a first read-out gate and ending with the last read-out gate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings that illustrate a specific embodiment of the invention. In the Drawings:

FIG. 1 is a diagram showing an enlarged view of an area of a FITCCD;

FIG. 2 is a diagram of voltage waveforms illustrating a conventional driving method;

FIG. 3 is a diagram showing the structure of a camera using a solid-state imaging apparatus according to a first embodiment;

FIG. 4 is a block diagram showing the structure of a solid-state imaging device 40 shown in FIG. 3;

FIG. 5 is a sectional view showing the structure of a part including a photodiode 41 and a vertical CCD 43 in the depth direction of a substrate;

FIG. 6 is a diagram showing a potential distribution in the substrate depth direction of the photodiode 41;

FIG. 7 is a diagram showing normal timings in a long-time accumulation mode;

FIG. 8 is a diagram showing the difference between fields on the appearance of white spots obtained by comparing the normal timings with the timings according to the present invention;

FIG. 9 is a diagram showing the difference between fields on the appearance of white spots obtained by comparing the normal timings with the timings according to the present invention;

FIG. 10 is a diagram showing the relationship between the timings indicating the drive dependency on the difference between fields on the appearance of white spots and the number of the white spots;

FIG. 11 is a diagram showing the relationship between the timings indicating the drive dependency on the difference between fields on the appearance of white spots and the number of the white spots;

FIG. 12 is a diagram showing the dependency of the position of the first change point of V8 in eight-phase driving;

FIG. 13 is a diagram showing an operation sequence from a long-time accumulation mode to the completion of plural-times of field transfer;

FIG. 14 is a sequence diagram showing the fine driving timings in a transition time period a in FIG. 13;

FIG. 15 is a diagram showing the operation timings of a V system executed around the time period β shown in FIG. 13;

FIG. 16 is a timing chart showing fine timings of a bias modulation of a substrate; and

FIG. 17 is a diagram showing the time dependency of transfer steps of injection suppression SUB.

Claims

1. A solid-state imaging apparatus comprising: a solid-state imaging device including a semiconductor substrate, photodiodes which are two-dimensionally formed on said semiconductor substrate, and vertical charge-coupled devices (CCDs) having at least one arranged read-out gate and non-read-out gate for each of said photodiodes, the read-out gate being for reading out accumulated electric charge from the associated photodiode, and the non-read-out gate being not for reading out accumulated electric charge from the associated photodiode; anda driving pulse control unit operable to control said solid-state imaging device by applying driving pulses to said respective read-out gates and non-read-out gates at predetermined timings,wherein said driving pulse control unit is operable to:apply driving pulses sequentially to said respective read-out gates in order to change said read-out gates from stand-by LOW-voltage states to MIDDLE-voltage states; andapply a driving pulse for maintaining a LOW-voltage state of at least one of non-read-out gates adjacent to a last read-out gate in an order of the change among said non-read-out gates, during the change starting with a first read-out gate and ending with the last read-out gate.

2. A solid-state imaging apparatus comprising: a solid-state imaging device including a semiconductor substrate, photodiodes which are two-dimensionally formed on said semiconductor substrate, and vertical CCDs having at least one arranged read-out gate and non-read-out gate for each of said photodiodes, the read-out gate being for reading out accumulated electric charge from the associated photodiode, and the non-read-out gate being not for reading out accumulated electric charge from the associated photodiode; anda driving pulse control unit operable to control said solid-state imaging device by applying driving pulses to said respective read-out gates and non-read-out gates at predetermined timings,wherein said solid-state imaging device is operable to read out electric charge accumulated in all of said photodiodes to said vertical CCDs by executing N-times of read-out operations, andsaid driving pulse control unit is operable to:apply driving pulses sequentially for changing N-numbers of read-out gates from stand-by LOW-voltage states to MIDDLE-voltage states; andapply a driving pulse for maintaining a LOW-voltage state of at least one of non-read-out gates adjacent to N-1th read-out gate and Nth read-out gate in an order of the change among said non-read-out gates, during the change starting with the N-1th read-out gate and ending with the Nth read-out gate.

3. A solid-state imaging apparatus comprising: a solid-state imaging device including a semiconductor substrate, photodiodes which are two-dimensionally formed on said semiconductor substrate, and vertical CCDs having at least one arranged read-out gate and non-read-out gate for each of said photodiodes, the read-out gate being for reading out accumulated electric charge from the associated photodiode, and the non-read-out gate being not for reading out accumulated electric charge from the associated photodiode; anda driving pulse control unit operable to control said solid-state imaging device by applying driving pulses to said respective read-out gates and non-read-out gates at predetermined timings,wherein said driving pulse control unit is operable to apply driving pulses sequentially to said respective read-out gates in order to change said read-out gates from stand-by LOW-voltage states to MIDDLE-voltage states simultaneously.

4. The solid-state imaging apparatus according to claim 3, wherein said driving pulse control unit is further operable to apply driving pulses for changing said non-read-out gates from MIDDLE-voltage states to LOW-voltage states in parallel with applying driving pulses for changing said read-out gates from stand-by LOW-voltage states to MIDDLE-voltage states.

5. The solid-state imaging apparatus according to claim 1, wherein said solid-state imaging device is operable to read out electric charge accumulated in all of said photodiodes to said vertical CCDs by executing N-times of read-out operations, andsaid driving pulse control unit is further operable to apply driving pulses for changing all of gates from LOW-voltage states to MIDDLE-voltage states at a starting time of transfer operation of a field or a frame, said gates being composed of N-numbers of read-out gates and at least N-numbers of non-read-out gates, and the application being executed as a transition operation preparatory to the transfer operation.

6. The solid-state imaging apparatus according to claim 5, wherein said driving pulse control unit is operable to execute the transition operation either (a) at a starting time of transferring a first field or (b) at a starting time of transferring said vertical CCDs at high speed.

7. The solid-state imaging apparatus according to claim 5, wherein said driving pulse control unit is further operable to:execute a first bias modulation and a second bias modulation, the first bias modulation being for accumulating signal electric charge up to a height of each read-out gate by changing an overflow barrier of said read-out gate to a high level before an end of an exposure time period, and the second bias modulation being for changing the height of the overflow barrier to a low level between the end of the exposure time period and a start of sweeping out of electric charge of said vertical CCDs; andexecute the transition operation between the end of the exposure time period and a start of the second bias modulation.

8. A solid-state imaging apparatus comprising: a solid-state imaging device including a semiconductor substrate, photodiodes which are two-dimensionally formed on said semiconductor substrate, and vertical CCDs having at least one arranged read-out gate and non-read-out gate for each of said photodiodes, the read-out gate being for reading out accumulated electric charge from the associated photodiode, and the non-read-out gate being not for reading out accumulated electric charge from the associated photodiode; anda driving pulse control unit operable to control said solid-state imaging device by applying driving pulses to said respective read-out gates and non-read-out gates at predetermined timings,wherein said driving pulse control unit is further operable to apply driving pulses for changing all of gates from LOW-voltage states to MIDDLE-voltage states at a starting time of transfer operation of a field or a frame, said gates being composed of N-numbers of read-out gates and at least N-numbers of non-read-out gates, and the application being executed as a transition operation preparatory to the transfer operation.

9. A method for driving a solid-state imaging apparatus which includes: a solid-state imaging device including a semiconductor substrate, photodiodes which are two-dimensionally formed on the semiconductor substrate, and vertical CCDs having at least one arranged read-out gate and non-read-out gate for each of the photodiodes, the read-out gate being for reading out accumulated electric charge from the associated photodiode, and the non-read-out gate being not for reading out accumulated electric charge from the associated photodiode; and a driving pulse control unit which controls the solid-state imaging device by applying driving pulses to the respective read-out gates and non-read-out gates at predetermined timings, said method comprising: a long-time accumulation mode for accumulating electric charge in each of the photodiodes during two or more vertical time periods; anda driving step of reading out electric charge accumulated in said long-time accumulation mode from each photodiode to the vertical CCDs, vertically transferring the electric charge, and outputting the electric charge,wherein in said long-time accumulation mode, nee of the driving according to claim 1 is executed.

10. A method for driving a solid-state imaging apparatus which includes: a solid-state imaging device including a semiconductor substrate, photodiodes which are two-dimensionally formed on the semiconductor substrate, and vertical CCDs having at least one arranged read-out gate and non-read-out gate for each of the photodiodes, the read-out gate being for reading out accumulated electric charge from the associated photodiode, and the non-read-out gate being not for reading out accumulated electric charge from the associated photodiode; and a driving pulse control unit which controls the solid-state imaging device by applying driving pulses to the respective read-out gates and non-read-out gates at predetermined timings, said method comprising: a long-time accumulation mode for accumulating electric charge in each of the photodiodes during two or more vertical time periods;a vertical CCD sweep-out mode for driving to transfer only the vertical CCDs before reading out electric charge accumulated in said long-time accumulation mode; anda driving step of reading out electric charge accumulated in said long-time accumulation mode from each photodiode to the vertical CCDs, vertically transferring the electric charge, and outputting the electric charge,wherein in said long-time accumulation mode, the driving according to claim 1 is executed.

11. A camera comprising a solid-state imaging apparatus according to claim 1.