Vision measuring device and auto-focusing control method

A vision measuring device, comprising:

• imaging device which images a measurement target and transfers image information representing an image of the measurement target;
• position control device which controls an in-focus position of the imaging device and outputs the in-focus position as position information representing a position in an in-focus axis direction;
• and
• vision measuring device which performs vision measurement on the measurement target based on the image information and the position information,
• wherein:
• the position control device acquires and retains the position information at a certain imaging timing of the imaging device;
• and
• the vision measuring device performs plural times of auto-focus searches along the in-focus axis direction by varying at least one of a moving velocity and a moving direction each time, obtains an amount of gap between the imaging timing and a timing at which the position information is acquired based on the image information transferred from the imaging device in each auto-focus search and the position information output from the position control device in each auto-focus search, and compensates for an in-focus position obtained in each auto-focus search based on the obtained amount of gap.

An auto-focusing control method of a vision measuring device comprising:

• imaging device which images a measurement target and transfers image information representing an image of the measurement target;
• position control device which controls an in-focus position of the imaging device and outputs the in-focus position as position information representing a position in an in-focus axis direction;
• and
• vision measuring device which performs vision measurement on the measurement target based on the image information and the position information, the method comprising:
• a step of the position control device acquiring and retaining the position information at a certain imaging timing of the imaging device;
• and
• a step of the vision measuring device performing plural times of auto-focus searches along the in-focus axis direction by varying at least one of a moving velocity and a moving direction each time, obtaining an amount of gap between the imaging timing and a timing at which the position information is acquired based on the image information transferred from the imaging device in each auto-focus search and the position information output from the position control device in each auto-focus search, and compensating for an in-focus position obtained in each auto-focus search based on the obtained amount of gap.