Automatic focusing apparatus and image pickup apparatus

Abstract

An automatic focusing apparatus performs focusing using a first automatic focusing method in which lens drive control is performed based on a focus signal so that a focus lens is moved to an in-focus point, and a second automatic focusing method in which lens drive control is performed based on information corresponding to an object distance so that the focus lens is moved to an in-focus point. The direction in which the focus lens is moved to the in-focus point according to the second automatic focusing method is compared with the direction in which the focus lens is moved to the in-focus point according to the first automatic focusing method. Based on the result, it is determined whether to perform the lens drive control according to the second automatic focusing method.

What is claimed is: 
     
       1. An image taking apparatus configured to perform focusing a first automatic focusing method in which a focus signal corresponding to the contrast of an image is obtained from an output signal of an image pickup unit and lens drive control is performed based on the focus signal so that a focus lens is moved to an in-focus point, and a second automatic focusing method in which information corresponding to object distance is obtained and lens drive control is performed based on the information so that the focus lens is moved to an in-focus point, the apparatus comprising:
 a panning-state-completion detecting unit configured to detect whether or not a panning state of the image taking apparatus is completed; and   a control unit configured to execute the lens drive control according to the second automatic focusing method in case where a moving direction of the focus lens according to the first automatic focusing method and the moving direction of the focus lens which corresponds to the object distance matches and also satisfying a predetermined condition in condition at a first time after completing the panning-state, and to execute the lens drive control according to the second automatic focusing method in case where satisfying the predetermined condition depending on whether or not the moving direction of the focus lens according to the first automatic focusing method and the moving direction of the focus lens which corresponds to the object distance matches in condition at a second time which is shorter than the first time after completing the panning-state.   
     
     
       2. The automatic focusing apparatus according to  claim 1 , wherein the control unit performs the lens drive control according to the second automatic focusing method and thereafter performs the lens drive control according to the first automatic focusing method when the difference between the information corresponding to object distance and the object distance corresponding to the present focus lens position is greater than the predetermined value. 
     
     
       3. The automatic focusing apparatus according to  claim 2 , wherein the control unit performs the lens drive control according to the first automatic focusing method without performing the lens drive control according to the second automatic focusing method when the difference between the information corresponding to object distance and the object distance corresponding to the present focus lens position is less than or equal to the predetermined value. 
     
     
       4. An image pickup apparatus having an automatic focusing apparatus configured to perform focusing a first automatic focusing method in which a focus signal corresponding to the contrast of an image is obtained from an output signal of an image pickup unit and lens drive control is performed based on the focus signal so that a focus lens is moved to an in-focus point, and a second automatic focusing method in which information corresponding to object distance is obtained and lens drive control is performed based on the information so that the focus lens is moved to an in-focus point, the image pickup apparatus comprising:
 an automatic focusing apparatus including,
 a panning-state-completion detecting unit configured to detect whether or not a panning state is completed; and 
 a control unit configured to execute the lens drive control according to the second automatic focusing method in case where a moving direction of the focus lens according to the first automatic focusing method and the moving direction of the focus lens which corresponds to the object distance matches and also satisfying a predetermined condition in condition at a first time after completing the panning-state, and to execute the lens drive control according to the second automatic focusing method in case where satisfying the predetermined condition depending on whether or not the moving direction of the focus lens according to the first automatic focusing method and the moving direction of the focus lens which corresponds to the object distance matches in condition at a second time which is shorter than the first time after completing the panning-state. 
   
     
     
       5. An image taking apparatus configured to perform focusing using a first automatic focusing method in which a first focus signal corresponding to the contrast of an image is obtained from an output signal of an image pickup unit and lens drive control is performed based on the first focus signal so that a focus lens is moved to an in-focus point, and a second automatic focusing method in which a second focus signal corresponding to object distance is obtained and lens drive control is performed based on the second focus signal so that the focus lens is moved to an in-focus point, the image taking apparatus comprising:
 a first determining unit configured to determine whether a predetermined time has elapsed after completion of the panning of the image taking apparatus;   a second determining unit configured to determine whether a first moving direction of the focus lens according to the first focus signal is same as a second moving direction of the focus lens according to the second focus signal;   a third determining unit configured to determine whether a predetermined condition is satisfied; and   a control unit configured to
 perform lens drive control based on the first and second focus signals in response to a determination result that the first moving direction is same as the second moving direction and a determination result that the predetermined condition has been satisfied in a case where it is determined that the predetermined time has elapsed after the completion of the panning, and 
 perform lens drive control based on the first and second focus signals in response to a determination result that the predetermined condition has been satisfied regardless of whether the first moving direction is same as the second moving direction in a case where it is determined that the predetermined time has not elapsed after the completion of the panning. 
   
     
     
       6. The image taking apparatus according to claim 5, wherein the difference between the object distance corresponding to the second focus signal obtained by the second automatic focusing method and the object distance corresponding to a current position of the focus lens is compared with a threshold to determine whether the predetermined condition is satisfied. 
     
     
       7. The image taking apparatus according to claim 5, wherein the first determining unit, the second determining unit, and the third determining unit are comprised with a microcomputer. 
     
     
       8. An image taking method performed by an image taking apparatus configured to perform focusing using a first automatic focusing method in which a first focus signal corresponding to the contrast of an image is obtained from an output signal of an image pickup unit and lens drive control is performed based on the first focus signal so that a focus lens is moved to an in-focus point, and a second automatic focusing method in which a second focus signal corresponding to object distance is obtained and lens drive control is performed based on the second focus signal so that the focus lens is moved to an in-focus point, the image taking method comprising:
 determining whether a predetermined time has elapsed after completion of the panning of the image taking apparatus;   determining whether a first moving direction of the focus lens according to the first focus signal is same as a second moving direction of the focus lens according to the second focus signal when it is determined that the predetermined time has elapsed after completion of the panning of the image taking apparatus;   determining whether a predetermined condition is satisfied in a case that it is determined that the first moving direction of the focus lens according to the first focus signal is same as the second moving direction of the focus lens according to the second focus signal and in a case that it is determined that the predetermined time has not elapsed after completion of the panning of the image taking apparatus;   performing lens drive control based on the first and second focus signals in response to a determination result that the first moving direction is same as the second moving direction and a determination result that the predetermined condition has been satisfied in a case where it is determined that the predetermined time has elapsed after the completion of the panning; and   performing lens drive control based on the first and second focus signals in response to a determination result that the predetermined condition has been satisfied regardless of whether the first moving direction is same as the second moving direction in a case where it is determined that the predetermined time has not elapsed after the completion of the panning.   
     
     
       9. The image taking method according to claim 8, wherein the difference between the object distance corresponding to the second focus signal obtained by the second automatic focusing method and the object distance corresponding to a current position of the focus lens is compared with a threshold to determine whether the predetermined condition is satisfied. 
     
     
       10. A computer-readable medium having stored thereon instructions for performing an image taking method by an image taking apparatus configured to perform focusing using a first automatic focusing method in which a first focus signal corresponding to the contrast of an image is obtained from an output signal of an image pickup unit and lens drive control is performed based on the first focus signal so that a focus lens is moved to an in-focus point, and a second automatic focusing method in which a second focus signal corresponding to object distance is obtained and lens drive control is performed based on the second focus signal so that the focus lens is moved to an in-focus point, the image taking method comprising:
 determining whether a predetermined time has elapsed after completion of the panning of the image taking apparatus;   determining whether a first moving direction of the focus lens according to the first focus signal is same as a second moving direction of the focus lens according to the second focus signal when it is determined that the predetermined time has elapsed after completion of the panning of the image taking apparatus;   determining whether a predetermined condition is satisfied in a case that it is determined that the first moving direction of the focus lens according to the first focus signal is same as the second moving direction of the focus lens according to the second focus signal and in a case that it is determined that the predetermined time has not elapsed after completion of the panning of the image taking apparatus;   performing lens drive control based on the first and second focus signals in response to a determination result that the first moving direction is same as the second moving direction and a determination result that the predetermined condition has been satisfied in a case where it is determined that the predetermined time has elapsed after the completion of the panning; and   performing lens drive control based on the first and second focus signals in response to a determination result that the predetermined condition has been satisfied regardless of whether the first moving direction is same as the second moving direction in a case where it is determined that the predetermined time has not elapsed after the completion of the panning.   
     
     
       11. The computer-readable medium according to claim 10, wherein the difference between the object distance corresponding to the second focus signal obtained by the second automatic focusing method and the object distance corresponding to a current position of the focus lens is compared with a threshold to determine whether the predetermined condition is satisfied.