Image pickup apparatus for minimizing variation in black level correction between plural outputs and a method of driving the same

Abstract

An image pickup apparatus includes an image sensor for photoelectrically converting light incident from a field to produce an image signal via al least two output portions. The temperature of the image sensor is sensed. The image sensor is driven such that the image signal is output via one of the output portions if the temperature sensed is higher than a predetermined value inclusive or is output via the two output portions if the former is lower than the latter. A black level corrector uses, when the image signal is output via one of the output portions, a predetermined single value as a reference to execute black level correction on the image signal, or uses, when the image signal is output via the two output portions, a particular predetermined value as a reference to execute black level correction on each of image signals output from respective output portions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become more apparent from consideration of the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic block diagram showing a preferred embodiment of the image pickup apparatus in accordance with the present invention;

FIG. 2 is a conceptual view of the image sensing surface useful for understanding a one-output and a two-output readout mode available with a CCD image sensor included in the illustrative embodiment shown in FIG. 1;

FIG. 3 is a conceptual view of a valid pixel region and an OB region constituting the image sensing surface of the CCD image sensor included in the illustrative embodiment and bisected in the right-and-left direction each specifically;

FIG. 4 is a flowchart useful for understanding a specific procedure of driving the image pickup apparatus in accordance with the illustrative embodiment;

FIG. 5 is a schematic block diagram, like FIG. 1, showing an alternative embodiment of the image pickup apparatus in accordance with the present invention;

FIG. 6 is a flowchart, like FIG. 4, useful for understanding a specific procedure of driving the image pickup apparatus shown in FIG. 5;

FIG. 7 is a schematic block diagram, like FIG. 1, showing another alternative embodiment of the image pickup apparatus in accordance with the present invention; and

FIG. 8 is a flowchart, like FIG. 4, useful for understanding a specific procedure of driving the image pickup apparatus shown in FIG. 7.

Claims

1. An image pickup apparatus comprising: an image sensor including a plurality of output portions and for photoelectrically converting light incident from a field to thereby produce an image signal via said plurality of output portions;a temperature sensor for sensing a temperature of said image sensor;a driver for driving said image sensor such that the image signal is output via one of said plurality of output portions if the temperature sensed by said temperature sensor is higher than a predetermined value inclusive or is output via at least two of said plurality of output portions if the temperature is lower than the predetermined value; anda black level corrector for using, when the image signal is output via one of said plurality of output portions, a predetermined single value as a reference to execute black level correction on the image signal, or using, when the image signal is output via at least two of said plurality of output portions, a particular predetermined value as a reference to execute black level correction on each of image signals output from respective output portions.

2. The apparatus in accordance with claim 1, wherein the predetermined single value comprises a shielded signal level of any subregion of a valid pixel region included in said image sensor while the particular predetermined value comprises a shielded level of each subregion of said valid pixel region in which the image signal to be output from the respective output portion is produced.

3. The apparatus in accordance with claim 1, wherein said plurality of output portions comprise two output portions.

4. The apparatus in accordance with claim 3, wherein said plurality of output portions are configured to output image signals produced in subregions defined by bisecting said valid pixel region in a right-and-left direction.

5. An image pickup apparatus comprising: an image sensor including a plurality of output portions and for photoelectrically converting light incident from a field to thereby produce an image signal via said plurality of output portions;a signal level monitor for monitoring a signal level of an optical black region surrounding a valid pixel region of said image sensor;a driver for driving said image sensor such that the image signal is output via one of said plurality of output portions if the signal level monitored by said signal level monitor is higher than a predetermined value inclusive or is output via at least two of said plurality of output portions if the signal level is lower than the predetermined value; anda black level corrector for using, when the image signal is output via one of said plurality of output portions, a predetermined single value as a reference to execute black level correction on the image signal or using, when the image signal is output via at least two of said plurality of output-portions, a particular predetermined value as a reference to execute black level correction on each of image signals output from respective output portions.

6. The apparatus in accordance with claim 5, wherein the predetermined single value comprises a shielded signal level of any subregion of a valid pixel region included in said image sensor while the particular predetermined value comprises a shielded level of each subregion of said valid pixel region in which the image signal to be output from the respective output portion is produced.

7. The apparatus in accordance with claim 5, wherein said plurality of output portions comprise two output portions.

8. The apparatus in accordance with claim 7, wherein said plurality of output portions are configured to output image signals produced in subregions defined by bisecting the valid pixel region in a right-and-left direction.

9. An image pickup apparatus comprising: an image sensor including a plurality of output portions and for photoelectrically converting light incident from a field to thereby produce an image signal via said plurality of output portions;a timer for counting a period of time over which said image sensor outputs an image signal for a through image of the field when a power supply is on;a driver for driving said image sensor such that the image signal is output via one of said plurality of output portions if the period of time counted by said timer is longer than a predetermined value inclusive or is output via at least two of said plurality of output portions if the period of time is shorter than the predetermined value; anda black level corrector for using, when the image signal is output via one of said plurality of output portions, a predetermined single value as a reference black to execute level correction on the image signal or using, when the image signal is output via at least two of said plurality of output portions, a particular predetermined value as a reference to execute black level correction on each of image signals output from respective output portions.

10. The apparatus in accordance with claim 9, wherein the predetermined single value comprises a shielded signal level of any subregion of a valid pixel region included in said image sensor while the particular predetermined value comprises a shielded level of each subregion of said valid pixel region in which the image signal to be output from the respective output portion is produced.

11. The apparatus in accordance with claim 9, wherein said plurality of output portions comprise two output portions.

12. The apparatus in accordance with claim 11, wherein said plurality of output portions are configured to output image signals produced in subregions defined by bisecting the valid pixel region in a right-and-left direction.

13. A method of driving an image pickup apparatus, comprising the steps of: sensing a temperature of an image sensor included in a pickup section and photoelectrically converting light incident from a field to thereby produce an image signal;outputting the image signal via one of a plurality of output portions included in the image sensor if the temperature sensed is higher than a predetermined value inclusive;outputting the image signal via at least two of the plurality of output portions if the temperature sensed is lower than the predetermined value;using, when the image signal is output via one of the plurality of output portions, a predetermined single value as a reference to execute black level correction on the image signal by; andusing, when the image signal is output via at least two of the plurality of output portions, a particular predetermined value as a reference to execute black level correction on each of image signals output from respective output portions.

14. The method in accordance with claim 13, wherein the predetermined single value comprises a shielded signal level of any subregion of a valid pixel region included in the image sensor while the particular predetermined value comprises a shielded level of each subregion of the valid pixel region in which the image signal to be output from the respective output portion is produced.

15. The method in accordance with claim 13, wherein the plurality of output portions comprise two output portions.

16. The method in accordance with claim 15, wherein the plurality of output portions are configured to output image signals produced in subregions defined by bisecting the valid pixel region in a right-and-left direction.

17. A method of driving an image pickup apparatus, comprising the steps of: measuring a signal level of an optical black region surrounding a valid pixel region of an image sensor included in a pickup section and photoelectrically converting light incident from a field to thereby produce an image signal;outputting the image signal via one of a plurality of output portions included in the image sensor if the signal level measured is higher than a predetermined value inclusive;outputting the image signal via at least two of the plurality of output portions if the signal level measured is lower than the predetermined value;using, when the image signal is output via one of the plurality of output portions, a predetermined single value as a reference to execute black level correction on the image signal; andusing, when the image signal is output via at least two of the plurality of output portions, a particular predetermined value as a reference to execute black level correction on each of image signals output from respective output portions.

18. The method in accordance with claim 17, wherein the predetermined single value comprises a shielded signal level of any subregion of a valid pixel region included in the image sensor while the particular predetermined value comprises a shielded level of each subregion of the valid pixel region in which the image signal to be output from the respective output portion is produced.

19. The method in accordance with claim 17, wherein the plurality of output portions comprise two output portions.

20. The method in accordance with claim 19, wherein the plurality of output portions are configured to output image signals produced in subregions defined by bisecting the valid pixel region in a right-and-left direction.

21. A method of driving an image pickup apparatus, comprising the steps of: counting a period of time over which an image sensor included in a pickup section outputs an image signal for a through image of a field when a power supply is on, the image sensor photoelectrically converting light incident from a field to thereby produce the image signal;outputting the image signal via one of a plurality of output portions included in the image sensor if the period of time counted is longer than a predetermined value inclusive;outputting the image signal via at least two of the plurality of output portions if the period of time counted is shorter than the predetermined value;using, when the image signal is output via one of the plurality of output portions, a predetermined single value as a reference to execute black level correction on the image signal; andusing, when the image signal is output via at least two of the plurality of output portions, a particular predetermined value as a reference to execute black level correction on each of image signals output from respective output portions.

22. The method in accordance with claim 21, wherein the predetermined single value comprises a shielded signal level of any subregion of a valid pixel region included in the image sensor while the particular predetermined value comprises a shielded level of each subregion of the valid pixel region in which the image signal to be output from the respective output portion is produced.

23. The method in accordance with claim 21, wherein the plurality of output portions comprise two output portions.

24. The method in accordance with claim 23, wherein the plurality of output portions are configured to output image signals produced in subregions defined by bisecting the valid pixel region in a right-and-left direction.