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A phase difference detection apparatus for detecting a phase difference between images formed on a pair of optical sensor arrays in which the possibility of unproductive compensation is reduced by use of a compensation effectiveness judgment unit that judges whether or not compensation of a pair of

A phase difference detection apparatus for detecting a phase difference between images formed on a pair of optical sensor arrays in which the possibility of unproductive compensation is reduced by use of a compensation effectiveness judgment unit that judges whether or not compensation of a pair of image data rows would be effective. A compensation unit calculates a compensation amount based on a difference in maximum values and minimum values in a pair of image data rows corresponding to the images produced by the optical sensor arrays and compensates the image data rows by the calculated compensation amount. Based upon the compensated values, a correlation calculation unit carries out a correlation calculation, and a maximum correlation detection unit detects a maximum correlation level. Based upon the maximum correlation level, a interpolation calculation unit carries out an interpolation calculation, and a phase difference is detected by a phase difference detection unit.

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1. A phase difference detection method comprising:a judgment step of judging whether or not a predetermined compensation would be effective for compensating an image data row which is generated in response to outputs of a pair of optical sensor arrays on which images of an object are formed;a first

1. A phase difference detection method comprising:a judgment step of judging whether or not a predetermined compensation would be effective for compensating an image data row which is generated in response to outputs of a pair of optical sensor arrays on which images of an object are formed;a first phase difference detection step of detecting a phase difference between the images formed on the pair of sensor arrays based upon the image data row when it is judged that the predetermined compensation would not be effective; anda second phase difference detection step of carrying out the predetermined compensation on the image data row when it is judged that the predetermined compensation would be effective and detecting a phase difference between the images formed on the pair of sensor arrays based upon the image data row after carrying out the predetermined compensation. 2. A phase difference detection method according to claim 1; wherein the judgment step comprises the step of judging that the predetermined compensation would be effective when an output waveform of one of the pair of optical sensor arrays is shifted in parallel with respect to an output waveform of the other optical sensor array; and the step of carrying out the predetermined compensation is performed based upon an amount of the shift. 3. A phase difference detection method according to claim 1; wherein the image data row is a pair of image data rows each comprising a plurality of image data values which are generated in response to the outputs of the pair of optical sensor arrays on which the images of the object are formed; the judgment step comprises the step of judging that the predetermined compensation would be effective when a difference between a difference in maximum image data values in each of the pair of image data rows and a difference in minimum image data values in each of the pair of image data rows falls within a predetermined range; and the second phase difference detection step of carrying out the predetermined compensation comprises the step of compensating the pair of image data rows by a compensation value determined based upon the difference in the maximum image data values and the difference in the minimum image data values. 4. A phase difference detection method according to claim 1; wherein the image data comprises a pair of image data rows each comprising a plurality of image data values which are generated by the pair of optical sensor arrays on which images of an object are formed; the judgment step comprises the step of judging that compensation would be effective when a difference between a difference in maximum image data values in each of the pair of image data rows and a difference in minimum image data values in each of the pair of image data rows falls within a predetermined range; and the second phase difference detection step of carrying out compensation comprises the step of compensating the pair of image data rows by a compensation value determined based upon the difference in the maximum image data values and the difference in the minimum image data values. 5. A phase difference detection apparatus comprising:a first judgment unit for judging whether or not a predetermined compensation would be effective for compensating an image data row which is generated in response to outputs of a pair of optical sensor arrays on which images of an object are formed;a first phase difference detection unit for detecting a phase difference between the images formed on the pair of sensor arrays based upon the image data row when it is judged by the first judgment unit that the predetermined compensation would not be effective;a second phase difference detection unit for carrying out the predetermined compensation with respect to the image data row when it is judged that the predetermined compensation would be effective and detecting a phase difference between the images formed on the pair of sensor arrays based upon the image data row after carrying out the predetermined compensation;a second judgement unit for judging whether or not the images formed on the pair of sensor arrays based on the image data row are affected by back-light; anda third chase difference detection unit for detecting a chase difference between the images formed on the pair of sensor arrays based upon the image data row when the second judgement unit judges that the images are not affected by back-light;wherein the first judgement unit carries out the judgement only when the second judgement unit judges that the images formed on the pair of sensor arrays are affected by back-light. 6. A range finding apparatus comprising: a phase difference detection apparatus according to claim 5; and a distance detection unit for calculating a distance to the object based upon a phase difference detected by the phase difference detection apparatus. 7. An imaging apparatus comprising: a phase difference detection apparatus according to claim 5; an objective lens; an image formation unit on which an image of the object is formed after passing through the objective lens; and a focusing control unit for carrying out a focusing operation between the objective lens and the image formation unit in response to the phase difference calculated by the phase difference detection apparatus. 8. A phase difference detection apparatus comprising:a first judgment unit for judging that a predetermined compensation would be effective for compensating an image data row which is generated in response to outputs of a pair of optical sensor arrays on which images of an object are formed by determining when an output waveform of one of the pair of optical sensor arrays is shifted in parallel with respect to an output waveform of the other optical sensor array;a first phase difference detection unit for detecting a chase difference between the images formed on the pair of sensor arrays based upon the image data row when it is not judged by the first judgment unit that the predetermined compensation would be effective; anda second phase difference detection unit for carrying out the predetermined compensation with respect to the image data row based on an amount of the shift when it is judged that the predetermined compensation would be effective and detecting a phase difference between the images formed on the pair of sensor arrays based upon the compensated image data row. 9. A phase difference detection apparatus according to claim 8; further comprising a second judgment unit for judging whether or not the images formed on the pair of sensor arrays based on the image data row are affected by back-light; and a third phase difference detection unit for detecting a phase difference between the images formed on the pair of sensor arrays based upon the image data row when the second judgment unit judges that the images are not affected by back-light; wherein the first judgment unit carries out the judgment only when the second judgment unit judges that the images formed on the pair of sensor arrays are affected by back-light. 10. A range finding apparatus comprising: a phase difference detection apparatus according to claim 8; and a distance detection unit for calculating a distance to the object based upon a phase difference detected by the phase difference detection apparatus. 11. An imaging apparatus comprising: a phase difference detection apparatus according to claim 8; an objective lens; an image formation unit on which an image of the object is formed after passing through the objective lens; and a focusing control unit for carrying out a focusing operation between the objective lens and the image formation unit in response to the phase difference calculated by the phase difference detection apparatus. 12. A phase difference detection apparatus comprising:a first judgment unit for judging that a predetermined compensation would be effective for compensating an image data row which is generated in response to outputs of a pair of optical sensor arrays on which images of an object are formed when a difference between a difference in maximum image data values in each of the pair of image data rows and a difference in minimum image data values in each of the pair of image data rows falls within a predetermined range;a first phase difference detection unit for detecting a phase difference between the images formed on the pair of sensor arrays based upon the image data row when it is not judged by the first judgment unit that the predetermined compensation would be effective; anda second chase difference detection unit for carrying out the predetermined compensation with respect to the image data row based upon the difference in the maximum image data values and the difference in the minimum image data values when it is judged that the predetermined compensation would be effective and detecting a phase difference between the images formed on the pair of sensor arrays based upon the compensated image data row. 13. A phase difference detection apparatus according to claim 12; further comprising a second judgment unit for judging whether or not the images formed on the pair of sensor arrays based on the image data row are affected by back-light; and a third phase difference detection unit for detecting a phase difference between the images formed on the pair of sensor arrays based upon the image data row when the second judgment unit judges that the images are not affected by back-light; wherein the first judgment unit carries out the judgment only when the second judgment unit judges that the images formed on the pair of sensor arrays are affected by back-light. 14. A range finding apparatus comprising: a phase difference detection apparatus according to claim 12; and a distance detection unit for calculating a distance to the object based upon a phase difference detected by the phase difference detection apparatus. 15. An imaging apparatus comprising: a phase difference detection apparatus according to claim 12; an objective lens; an image formation unit on which an image of the object is formed after passing through the objective lens; and a focusing control unit for carrying out a focusing operation between the objective lens and the image formation unit in response to the phase difference calculated by the phase difference detection apparatus. 16. A phase difference detection apparatus according to claim 12; further comprising a correlation calculation unit for performing correlation calculation by extracting partial image data groups from the pair of image data rows and determining a maximum correlation level therebetween. 17. A phase difference detection apparatus according to claim 16; wherein the correlation calculation unit performs correlation calculation by extracting a fixed partial image data group from one of the pair of image data rows, and extracting different partial image data groups from the other image data row, and comparing the extracted partial image data groups. 18. A phase difference detection apparatus according to claim 16; further comprising an interpolation calculation unit for compensating the maximum correlation level by performing an interpolation technique thereon. 19. A phase difference detection apparatus according to claim 18; wherein the second phase difference detection unit detects a shift amount from a reference position of the compensated maximum correlation level. 20. A phase difference detection apparatus according to claim 19; further comprising a reliability judgment unit for judging whether the compensated maximum correlation level is larger than a predetermined value; and wherein the second phase difference compensation unit performs compensation on the phase difference if the compensated maximum correlation level is lower than the predetermined value. 21. A range finding apparatus comprising:a pair of spaced-apart lenses for forming first and second images of an object spaced by a given distance from t he respective lenses;a pair of optical sensor arrays respectively arranged behind the lenses relative to the object for producing first and second output signals corresponding to the images formed by the lenses;an A/D converter for converting the first and second output signals of the optical sensor arrays into corresponding first and second digital signals;a memory unit for storing the digital signals;a judgment unit for calculating a first difference in average values of the first and second digital signals and judging whether or not the first difference exceeds a first predetermined value;a compensation effectiveness unit for performing a compensation effectiveness determination if the first difference exceeds the first predetermined value by calculating a second difference between a maximum value of the first digital signal and a maximum value of the second digital signal and a third difference between a minimum value of the first digital signal and a minimum value of the second digital signal, judging whether or not a fourth difference between the second difference and the third difference exceeds a second predetermined value, and determining that compensation would be effective if the fourth difference exceeds the second predetermined value;a compensation unit for calculating a compensation value if the fourth difference exceeds the second predetermined value and compensating the stored digital signals stored in the memory based on the compensation value;a correlation calculation unit for performing correlation calculation by extracting partial image data groups from the first and second digital signals stored in the memory and determining a maximum correlation level therebetween;an interpolation calculation unit for compensating the maximum correlation level by performing an interpolation technique; anda phase difference detection unit for detecting a shift amount from a reference position of the compensated maximum correlation level. 22. A range finding apparatus according to claim 21; wherein the compensation unit calculates the compensation value by dividing by 2 a sum of the second difference and the third difference. 23. A range finding apparatus according to claim 21; further comprising a reliability judgment unit for judging whether the compensated maximum correlation level is larger than a third predetermined value; and a phase difference compensation unit for compensating the phase difference if the compensated maximum correlation level is lower than the third predetermined value. 24. A phase difference detection method comprising:a judgment step of judging whether or not compensation would be effective for compensating image data which is generated by a pair of optical sensor arrays by comparing outputs of the pair of optical sensor arrays;a first phase difference detection step of detecting a phase difference between the image data generated by the pair of optical sensor arrays without performing compensation when it is judged that compensation would not be effective; anda second phase difference detection step of carrying out compensation on the image data when it is judged that compensation would be effective and detecting a phase difference between the image data generated by the pair of optical sensor arrays based upon the compensated image data. 25. A phase difference detection method according to claim 24; wherein the judgment step comprises the step of judging that compensation would be effective when an output waveform of one of the pair of optical sensor arrays is shifted in parallel with respect to an output waveform of the other optical sensor array; and the step of carrying out compensation is performed based upon an amount of the shift.