Television – Camera – system and detail – Solid-state image sensor
Reexamination Certificate
1994-04-01
2001-07-10
Garber, Wendy (Department: 2712)
Television
Camera, system and detail
Solid-state image sensor
C348S088000
Reexamination Certificate
active
06259478
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to video imaging devices used to capture images of objects on a sequential basis. More particularly, this invention relates to triggered image capturing devices using a camera with solid state video imaging technology.
Solid state video imaging devices are known which are designed to capture still images of objects in a time sequential manner. Such devices are usually triggered either internally or externally by means of trigger pulses, which are either generated on a regular periodic basis or in response to the external generation of a trigger pulse in response to the passage of an object past a triggering point. Typical uses of such devices are in industrial applications in which it is desired to capture static images of moving objects along an assembly line, a conveyor belt or the like.
In known systems, a video camera using a charge coupled device (CCD) imaging element is installed at an observation point and is triggered either on a regular timed interval or in response to a triggering signal generated by a monitoring device (such as a photoelectric sensor) whenever an object is properly positioned in the observation area. In response to the trigger signal, an electronic image is captured by the CCD in the form of stored charges which are then converted into appropriate analog video signals. These video signals are then processed by follow on signal processing circuitry external to the camera and subsequently coupled to appropriate display and storage devices, such as a video monitor, a video tape recorder or the like.
While effective in many applications, known CCD based systems suffer from limited image resolution due to two factors. The first factor is inherent in the construction of conventional CCD video cameras with CCD elements having a lateral overflow drain structure. At the beginning of each imaging cycle, any charges accumulated in each pixel region of the CCD imaging element must initially be discharged prior to beginning development of the desired image (to remove background noise). With CCD devices having lateral overflow drain structure, the duration of the minimum discharge period is such that the practical shutter speed is limited to about {fraction (1/2000)}th second. For application requiring a faster shutter speed, such as objects traveling along a belt conveyor at a rapid speed or on-line inspection installations, the required shutter speed ranges from a minimum of {fraction (1/4000)}th second to {fraction (1/30000)}th second in order to provide a static image of the moving object with sufficient resolution. The second factor lies in the normal format arrangement employed in conventional CCD video cameras: such cameras typically produce video in an interlaced format in which each frame is divided into two successive fields, as in the standard NTSC video signal format. With this type of video formatting, the resolution obtained for each image is only that of one field, which is approximately one-half the resolution of a full frame. Thus, even if the initial discharge period of such devices were somehow decreased by an amount sufficient to permit shutter speeds in the required range, the resolution of the image obtained would not meet the quality standards required for many applications.
Efforts to date to design electronically shuttered solid state video imaging devices devoid of the above disadvantages have not met with success to date.
SUMMARY OF THE INVENTION
The invention comprises a solid state video imaging device with improved image resolution, which is capable of relatively fast shutter speeds over a wide range and which provides full frame resolution for a captured image, interlaced or non-interlaced video output signals, and an externally controllable shutter speed.
In its broadest aspect, the invention comprises an electronic shutter camera with full frame resolution comprising a progressive scanning interline transfer charge coupled device (CCD) for imaging a frame of information; timing means for generating electronic shutter signals for controlling the scanning and charge transfer rate for the CCD; control means for resetting the timing means; memory means for storing a full frame image from the CCD; and means for converting the full frame image to video signals having a selected format. The CCD preferably has a vertical overflow drain structure.
The control means may alternatively include manually selectable means for specifying the shutter speed, or means responsive to a pair of externally supplied pulses for selecting the shutter speed in accordance with the time separation between preselected portions of the pair of externally supplied pulses.
The converting means preferably includes means for outputting the frame image as either interlaced successive fields of video information or as a non-interlaced frame of video information.
The control means further preferably includes means responsive to an externally supplied asynchronous reset signal for resetting the timing means.
The memory means preferably comprises a digital storage device having a memory capacity of at least one frame of information, and an analog to digital converter coupled between the CCD and the digital storage device for converting the CCD analog output signals to digital equivalent signals.
The converting means preferably includes a digital to analog converter coupled to the digital storage device for converting digital equivalent signals stored in the digital storage device to analog video output signals. The converting means preferably further includes means for accessing the digital equivalent signals in the digital storage device in either a pixel sequential alternate line sequential order or a pixel sequential line sequential order, so that the analog video output signals are output respectively in interlaced format as odd and even fields or output in a non-interlaced format.
For a fuller understanding of the nature and advantages of the invention, reference should be had to the ensuing detailed description taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4531156 (1985-07-01), Nishizawa et al.
patent: 4794453 (1988-12-01), Gnuechtel et al.
patent: 4851915 (1989-07-01), Yang et al.
patent: 4896211 (1990-01-01), Hunt et al.
patent: 5153730 (1992-10-01), Nagasaki et al.
patent: 5298734 (1994-03-01), Kokubo
Christensen Andrew B.
Garber Wendy
LandOfFree
Full frame electronic shutter camera does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Full frame electronic shutter camera, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Full frame electronic shutter camera will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2479711