Method of and apparatus for inspecting transparent object for defect

An apparatus for inspecting a transparent or translucent object for a defect, comprising:

• a reference pattern carrier having thereon a reference pattern such as a moire wherein the bright and the dark appear successively and regularly at a predetermined pitch;
• a light source for irradiating light upon said reference pattern carrier;
• an image sensor in the form of a solid-state image pickup element for receiving light of the reference pattern transmitted through said reference pattern carrier;
• memory means for receiving and storing therein data of picture elements from said image sensor;
• reference pattern pitch detecting means for detecting the pitch of the reference pattern from numbers of picture element data of the bright and the dark from said memory means which have been obtained from an image of the reference pattern received directly or by way of a normal transparent article by said image sensor;
• average value calculating means for calculating an average value between those two of the picture element data of the reference pattern from said memory means obtained from an image of the reference pattern received through an object by said image sensor which are spaced by a predetermined number of picture elements with reference to the pitch detected by said reference pattern pitch detecting means;
• threshold value setting means for setting upper and lower threshold values from the average value;
• reference pattern erasing means for successively comparing the picture element data from said memory means with the upper and lower threshold values to determine the picture element data as the dark when the picture element data fall between the upper and lower threshold values but determine the picture element data as the bright in any other case to erase data based on the reference pattern;
• bright/dark determining means for counting numbers of data of those picture elements in a unit area around each of the picture elements which are determined as the bright and the dark and determining the bright or the dark of the picture element in accordance with a difference between the thus counted numbers;
• and
• defect discriminating means for discriminating a defect from numbers of data of picture elements of the bright and the dark determined by said bright/dark determining means.

An equipment for inspecting a transparent or translucent object for a defect, comprising:

• means for successively positioning an object at first, second and third inspecting positions;
• an optical system provided for each of the first, second and third inspective positions for projecting light of a reference pattern diametrically upon an object at the inspecting position over an angle of about 60 degrees around an axis of the object and photographing light transmitted through the object to obtain data of picture elements of an image of the received light;
• a rotating apparatus interposed between the first and second inspecting positions and between the second and third inspecting positions for rotating an object by 60 degrees in one direction around its axis;
• and
• a picture image processing apparatus connected to each or all of the optical systems for detecting a defect of an object from the data of picture elements from said optical system or systems, wherein said picture image processing apparatus or each of said picture image processing apparatus includes:
• memory means for receiving and storing therein data of picture elements from the corresponding optical system or the optical systems;
• reference pattern pitch detecting means for detecting the pitch of the reference pattern from numbers of picture element data of the bright and the dark from said memory means which have been obtained from an image of the reference pattern received directly or by way of a normal transparent article by said optical system;
• average value calculating means for calculating an average value between those two of the picture element data of the reference pattern from said memory means obtained from an image of the reference pattern received through an object by said optical system which are spaced by a predetermined number of picture elements with reference to the pitch detected by said reference pattern pitch detecting means;
• threshold value setting means for setting upper and lower threshold values from the average value;
• reference pattern erasing means for successively comparing the picture element data from said memory means with the upper and lower threshold values to determine the picture element data as the dark when the picture element data fall between the upper and lower threshold values but determine the picture element data as the bright in any other case to erase data based on the reference pattern;
• bright/dark determining means for counting numbers of data of those picture elements in a unit area around each of the picture elements which are determined as the bright and the dark and determining the bright or the dark of the picture element in accordance with a difference between the thus counted numbers;
• and
• defect discriminating means for discriminating a defect from numbers of data of picture elements of the bright and the dark determined by said bright/dark determining means.

An equipment for inspecting a transparent or translucent object for a defect, comprising:

• means for successively positioning an object at a pair of inspecting positions;
• first and second optical systems provided for one of the inspecting positions for projecting light of a reference pattern diametrically upon an object at the inspecting position over different contiguous angular ranges of about 60 degrees around an axis of the object and photographing light transmitted through the object to obtain data of picture elements of images of the received light;
• a third optical system provided for the other of the inspecting positions for projecting light of the same reference pattern diametrically upon an object at the inspecting position over an angular range of about 60 degrees around the axis of the object and photographing light transmitted through the object to obtain data of picture elements of an image of the received light;
• a rotating apparatus interposed between the inspecting positions for rotating an object by 60 degrees in one direction around its axis so that said first, second and third optical systems may photograph different contiguous angular ranges of an object;
• and
• a picture image processing apparatus connected to each or all of said first to third optical systems for detecting a defect of an object from the data of picture elements from said optical system or systems, wherein said picture image processing apparatus or each of said picture image processing apparatus includes:
• memory means for receiving and storing therein data of picture elements from the corresponding optical system or the optical systems;
• reference pattern pitch detecting means for detecting the pitch of the reference pattern from numbers of picture element data of the bright and the dark from said memory means which have been obtained from an image of the reference pattern received directly or by way of a normal transparent article by said optical system;
• average value calculating means for calculating an average value between those two of the picture element data of the reference pattern from said memory means obtained from an image of the reference pattern received through an object by said optical system which are spaced by a predetermined number of picture elements with reference to the pitch detected by said reference pattern pitch detecting means;
• threshold value setting means for setting upper and lower threshold values from the average value;
• reference pattern erasing means for successively comparing the picture element data from said memory means with the upper and lower threshold values to determine the picture element data as the dark when the picture element data fall between the upper and lower threshold values but determine the picture element data as the bright in any other case to erase data based on the reference pattern;
• bright/dark determined means for counting numbers of data of those picture elements in a unit area around each of the picture elements which are determined as the bright and the dark and determining the bright or the dark of the picture element in accordance with a difference between the thus counted numbers;
• and
• defect discriminating means for discriminating a defect from numbers of data of picture elements of the bright and the dark determined by said bright/dark determining means.

An equipment for inspecting a transparent or translucent object for a defect, comprising:

• means for successively positioning an object at an inspecting position;
• first, second and third optical systems provided for the inspecting position for projecting light of a reference pattern diametrically upon an object at the inspecting position over different contiguous angular ranges of about 60 degrees around an axis of the object and photographing light transmitting through the object to obtain data of picture elements of images of the received light;
• and
• a picture image processing apparatus connected to each or all of said first to third optical systems for detecting a defect of an object from the data of picture elements from said optical system or systems, wherein said picture image processing apparatus or each of said picture image processing apparatus includes:
• memory means for receiving and storing therein data of picture elements from the corresponding optical system or the optical systems;
• reference pattern pitch detecting means for detecting the pitch of the reference pattern from numbers of picture element data of the bright and the dark from said memory means which have been obtained from an image of the reference pattern received directly or by way of a normal transparent article by said optical system;
• average value calculating means for calculating an average value between those two of the picture element data of the reference pattern from said memory means obtained from an image of the reference pattern received through an object by said optical system which are spaced by a predetermined number of picture elements with reference to the pitch detected by said reference pattern pitch detecting means;
• threshold value setting means for setting upper and lower threshold values from the average value;
• reference pattern erasing means for successively comparing the picture element data from said memory means with the upper and lower threshold values to determined the picture element data as the dark when the picture element data fall between the upper and lower threshold values but determined the picture element data as the bright in any other case to erase data based on the reference pattern;
• bright/dark determining means for counting numbers of data of those picture elements in a unit area around each of the picture elements which are determined as the bright and the dark and determining the bright or the dark of the picture element in accordance with a difference between the thus counted numbers;
• and
• defect discriminating means for discriminating a defect from numbers of data of picture elements of the bright and the dark determined by said bright/dark determining means.