Television – Image signal processing circuitry specific to television – Noise or undesired signal reduction
Reexamination Certificate
1998-03-18
2001-10-30
Powell, Mark R. (Department: 2672)
Television
Image signal processing circuitry specific to television
Noise or undesired signal reduction
C348S615000, C348S617000, C348S618000, C386S349000, C386S349000, C386S349000, C386S349000
Reexamination Certificate
active
06310660
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to video signal monitoring and detection. In particular, the invention relates to an electronic video signal dropout detector for consumer video equipment such as video tape players.
BACKGROUND
Video equipment, such as video cassette recorder/players (“VCR”) and camcorders, have become so popular as to be nearly ubiquitous. The vast number of consumers owning and operating such equipment has naturally increased the need for servicing and repairing such equipment, thus putting inordinate demands on qualified service technicians. Accordingly, a technician's time in diagnosing and correcting reported problems with video equipment is extremely valuable.
Among the more common video equipment problems reported by consumers, and resulting in the return of such equipment to the manufacturer, is video signal dropout. Video signal dropout is a usually momentary loss or interruption in the video signal emanating from the equipment, and may manifest itself on a video monitor as glitches or instantaneous blackout of the transmitted image.
Since video signal dropout is usually intermittent, technicians are frequently unable to detect and correct the problem. Furthermore, from a practical standpoint, the technician is simply unable to devote the time necessary to manually test each unit. Manual testing requires the technician to watch a video monitor for an extended period of time in hopes of seeing evidence of signal dropout, a procedure that the demands of production schedules clearly prohibit.
It can be seen from the foregoing that the need exists for a video dropout detector that will reliably identify the occurrence and frequency of occurrence of video signal dropout without requiring the constant presence or attention of a technician.
SUMMARY
One embodiment of the present invention provides a method of detecting video signal dropout. The method includes the step of receiving a video signal, and electronically isolating at least one component of the video signal. The at least one component is representative of the absence of the video signal itself. The absence of the at least one component is electronically sensed as an indication of dropout. In the preferred embodiment, the determination of the absence of the at least one component is determined by comparing the signal to an upper and a lower threshold to establish the presence or absence of the signal within a window of values.
The step of electronically isolating can include the step of passing the video signal through a comb filter, and in particular isolating a luminescence signal from the video signal. The step of electronically isolating can also include passing the video signal through a sync separator. The step of electronically sensing can include passing the at least one component through a comparator.
The method can also include the step of generating an audio signal to indicate the end of the predetermined time duration. In this embodiment, the step of electronically sensing is then terminated in response to the audio signal. The audio signal may be provided as part of a test tape.
A video signal dropout detector is also described. The detector is adapted to be connected to a video signal source, and includes an isolation assembly, connected to the video signal source, for isolating at least one signal component from a video signal generated by the video signal source. A sensing device is connected to the isolation assembly, and is equipped to sense an interruption in the at least one signal component. The at least one signal component is selected such that an interruption in the at least one signal component corresponds to a dropout of the video signal generated by the video signal source. The video signal may be provided by a test tape.
The isolation assembly can include a comb filter, and the at least one signal component can be isolated by passing the video signal through the comb filter. The comb filter can be used to isolate a luminescence component of the video signal. The isolation assembly can also include a video sync separator. The sensing device can include a comparator. A microcontroller can be connected to the sensing device and the destination device.
A test tape having a test pattern, such as an all green raster, is preferably used in conducting the test. The test tape includes audio signals used to indicate the beginning and end of the test.
The features of the invention believed to be patentable are set forth with particularity in the appended claims. The invention itself, however, both as to organization and method of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings.
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Abuali Khaled Amin
Yazurlo Donato
Powell Mark R.
Sajous Wesner
Sony Corporation
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