Television – Special applications – Manufacturing
Reexamination Certificate
1998-07-20
2001-04-24
Le, Vu (Department: 2613)
Television
Special applications
Manufacturing
C348S126000
Reexamination Certificate
active
06222582
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an image capture system for capturing image signals representative of a plurality of divided images of an object photographed by a camera.
2. Description of the Prior Art
An inspection step for circuit substrates is conventionally provided with an inspection system including a camera for photographing wire-bonded parts or portions etc. of a substrate surface, for example. In this inspection system, an image of a minute wire-bonded part is difficult to be recognized when the overall circuit substrate is photographed so as to come into the range of the camera. Accordingly, parts of the circuit substrate to be inspected are photographed as respective enlarged images. The circuit substrate usually includes a plurality of parts to be inspected. The camera or the circuit substrate is moved horizontally so that different parts to be inspected are photographed.
In the above-described inspection system, however, it is difficult to capture images of a plurality of different parts to be inspected at high speeds since moving the camera or the circuit substrate takes much time. Consequently, the above-described inspection system cannot meet the requirement of high speed processing.
To solve the above-described drawback, the prior art has provided a system in which a plurality of cameras are set for each of the parts to be inspected so that images of different parts photographed by the respective cameras are captured. In this system, however, a plurality of cameras cannot be juxtaposed when the parts to be inspected are located near to one another. Accordingly, this system cannot be applied to an inspection system for small components such as the circuit substrates.
Japanese Unexamined Patent Publication No. 8-233554 (1996) discloses a system including two galvanometer mirrors disposed above the object to be inspected. A part of the object is reflected on the galvanometer mirrors in turn, and angles of the galvanometer mirrors relative to the object is switched at a predetermined frequency so that the part of the object to be reflected on the galvanometer mirrors is changed. Two lenses are disposed in front and in the rear of the galvanometer mirrors respectively. Parts of the object reflected on the galvanometer mirrors in turn are sequentially photographed by the camera in synchronization with the changes in the angles of the galvanometer mirrors. Consequently, images of the entire object with a large area can be captured at a high speed.
In the disclosed system, one of the galvanometer mirrors has a wide changing range of its angle (swing angle) for the purpose of photographing an object with a large area. Accordingly, a distance between the part to be photographed and the galvanometer mirror is varied to a large extent with the change in the angle of the galvanometer mirror. This results in variations in the length of an optical path between the part to be photographed and the camera to a large extent. The variations in the length of the optical path result in an unfocused image photographed by the camera. In the disclosed system, the two lenses are disposed in front and in the rear of the galvanometer mirrors respectively to compensate a focal length. However, provision of these lenses complicates the arrangement of the optical system and increases the cost of the system.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an image capture system for capturing image signals representative of a plurality of divided images of an object photographed by a camera, wherein the arrangement of the optical system can be simplified.
To achieve the object, the present invention provides an image capture system comprising at least one movable mirror disposed over an object so as to reflect a part of the object to be photographed, a mirror driver for changing an angle of the movable mirror relative to the object so that the part of the object reflected on the movable mirror is changed to another part of the object to be photographed, a control circuit for controlling the mirror driver, a camera for photographing the part of the object reflected on the movable mirror, an image processor capturing an image signal from the camera every time the angle of the movable mirror is changed, and means for locating the movable mirror a predetermined value or above higher than the object so that the image photographed by the camera is prevented from being unfocused upon angular change in the movable mirror. In order that the image photographed by the movable camera may be prevented from being unfocused due to an angular change of the movable mirror, the movable mirror is preferably located higher than the object by 30 centimeters or more.
The movable mirror is located higher than the object so that the swing angle thereof is decreased. The distance between the part of the object to be photographed and the movable mirror varies with the change in the angle of the movable mirror. In the above-described arrangement, however, the variations in the distance are decreased so that the variations in the length of the optical path between the part of the object to be photographed and the camera are reduced. Consequently, the image photographed by the camera is prevented from being unfocused. Furthermore, since the swing angle of the movable mirror is reduced, even the part in the periphery of the object can accurately be photographed at nearly a right angle to the camera.
In a preferred form, the image processor comprises a plurality of image processing units whose number is equal to or smaller than the number of parts of the object to be photographed. The image processing units deliver to the control circuit photographing request signals requesting different parts of the object to be photographed respectively. The control circuit controls the mirror driver in response to the photographing request signal from each image processing unit so that the angle of the movable mirror is changed. The camera photographs the requested part of the object to be photographed after completion of the angular change in the movable mirror, each image-processing unit having delivered the photographing request signal captures an image signal from the camera. Consequently, the image signal representative of an optional part of the object can be captured at high speeds. Furthermore, the image signals representative of a plurality of parts of the object can be processed by a plurality of image processing units in a parallel processing mode respectively. This provides a high speed image processing for the entire object.
In another preferred from, upon completion of the angular change of the movable mirror, the control circuit delivers a ready signal to the image processing unit having delivered the photographing request signal, thereby informing an image signal capture timing. Based on the receipt of the ready signal, each image processing unit can accurately judge the timing for capturing the image signal from the camera.
In further another preferred form, each image processing unit compares the captured image of the object to be photographed with a predetermined reference imager thereby inspecting an appearance and/or dimensions of the photographed part of the object. Alternatively, each image processing unit performs an operation for obtaining at least one of an area, outside dimensions, and coordinates of the captured image of the part of the object, thereby inspecting an appearance and/or dimensions of the photographed part of the object on the basis of results of the operation. In this arrangement, each image processing unit can execute processes from the capture of the image signal to the inspection of each part of the object at high speeds.
Other objects, features and advantages of the present invention will become clear upon reviewing the following description of the preferred embodiment thereof.
REFERENCES:
patent: Re. 35816 (1998-06-01), Schulz
patent: 5276546 (1994-01-01), Palm et al.
patent: 5841539 (1998-11-01), Ikur
Foley & Lardner
Le Vu
Sumitomo Metal (SMI) Electronics Devices Inc.
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