US5748252A
Expired / Lapsed
US
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Method and apparatus for synchronizing internal and external video signals
Assignee: Delphi Technologies Inc
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Filing: 1996-02-20
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Granted: 1998-05-05
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Expires: 2016-02-20
Abstract
Abstract An automotive video display of a scene from a camera has a graphics window to display vehicle information. A video graphics controller has a programmable synchronous generator for the graphics window which is synchronized or gen-locked with the camera or external video signal. A digital sync separator provides digital external sync signals. A start circuit monitors the external sync signals to detect the start of a video frame and starts the sync generator which is initially in synchronism with the external signal. A phase locked loop maintains the synchronism. A crystal oscillator circuit includes an inductor and a varactor which is tuned to vary the oscillator frequency enough to track the external video signal.
Inventors
- 👤 Kenneth George Draves
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:51
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/04; H04N5/12; H04N5/126
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
158 words
A method of synchronizing a programmable sync generator output with an external video signal where the sync generator frequency is controlled by a voltage controlled oscillator comprising the steps of: detecting the beginning of a frame in the video signal by digitizing the video signal, monitoring the digitized signal for determining the beginning of a frame, producing a start pulse for starting the sync generator at the beginning of a frame, and after one start pulse is produced, inhibiting any additional start pulses so long as the video signal is present; starting the sync generator when the frame begins so that initially the sync generator output signal is synchronized with the video signal; comparing the phases of the output signal and the video signal and generating a voltage according to phase differential; and adjusting the voltage controlled oscillator with the generated voltage to null the phase differential, whereby the output signal is synchronized with the external video signal.
Claim 2
Independent Claim
158 words
A method of synchronizing a programmable sync generator output with an external video signal where the sync generator frequency is controlled by a voltage controlled oscillator comprising the steps of: detecting the beginning of a frame in the video signal by digitizing the video signal, monitoring the digitized signal for determining the beginning of a frame, producing a start pulse for starting the sync generator at the beginning of a frame, and after one start pulse is produced, inhibiting any additional start pulses so long as the video signal is present; starting the sync generator when the frame begins so that initially the sync generator output signal is synchronized with the video signal; comparing the phases of the output signal and the video signal and generating a voltage according to phase differential; and adjusting the voltage controlled oscillator with the generated voltage to null the phase differential, whereby the output signal is synchronized with the external video signal.
Claim 3
Independent Claim
141 words
A method of synchronizing a programmable sync generator output with an external video signal wherein the beginning of a frame is indicated by the beginning of an odd field and where the sync generator frequency is controlled by a voltage controlled oscillator comprising the steps of: detecting the beginning of a frame in the video signal by digitizing the video signal, and monitoring the digitized signals for determining the beginning of an odd field; starting the sync generator when the frame begins so that initially the sync generator output signal is synchronized with the video signal; comparing the phases of the output signal and the video signal and generating a voltage according to phase differential; and adjusting the voltage controlled oscillator with the generated voltage to null the phase differential, whereby the output signal is synchronized with the external video signal.
Claim 4
Independent Claim
141 words
A method of synchronizing a programmable sync generator output with an external video signal wherein the beginning of a frame is indicated by the beginning of an odd field and where the sync generator frequency is controlled by a voltage controlled oscillator comprising the steps of: detecting the beginning of a frame in the video signal by digitizing the video signal, and monitoring the digitized signals for determining the beginning of an odd field; starting the sync generator when the frame begins so that initially the sync generator output signal is synchronized with the video signal; comparing the phases of the output signal and the video signal and generating a voltage according to phase differential; and adjusting the voltage controlled oscillator with the generated voltage to null the phase differential, whereby the output signal is synchronized with the external video signal.
Claim 5
Independent Claim
152 words
A method of synchronizing a programmable sync generator output with an external video signal where the sync generator frequency is controlled by a voltage controlled oscillator comprising the steps of: detecting the beginning of a frame in the video signal by digitizing the video signal to obtain composite and vertical sync signals and an odd/even field signal, and monitoring the pulse width of the composite sync signal and the states of the vertical sync signal and the field signal for the start of a frame; starting the sync generator when the frame begins so that initially the sync generator output signal is synchronized with the video signal; comparing the phases of the output signal and the video signal and generating a voltage according to phase differential; and adjusting the voltage controlled oscillator with the generated voltage to null the phase differential, whereby the output signal is synchronized with the external video signal.
Claim 6
Independent Claim
152 words
A method of synchronizing a programmable sync generator output with an external video signal where the sync generator frequency is controlled by a voltage controlled oscillator comprising the steps of: detecting the beginning of a frame in the video signal by digitizing the video signal to obtain composite and vertical sync signals and an odd/even field signal, and monitoring the pulse width of the composite sync signal and the states of the vertical sync signal and the field signal for the start of a frame; starting the sync generator when the frame begins so that initially the sync generator output signal is synchronized with the video signal; comparing the phases of the output signal and the video signal and generating a voltage according to phase differential; and adjusting the voltage controlled oscillator with the generated voltage to null the phase differential, whereby the output signal is synchronized with the external video signal.
Claim 7
Dependent Claim
74 words
The invention as defined in claim 3 wherein the composite sync signal comprises standard width pulses during a field scan and short pulses at the beginning of each field, and wherein the step of monitoring the pulse width comprises: generating reference pulses having a pulse width between the widths of the standard and short width pulses; and comparing each pulse of the composite sync signal to a reference pulse to detect the short pulses.
Claim 8
Dependent Claim
34 words
The invention as defined in claim 4 wherein the states of the vertical sync signal and the odd/even field signal determine which of the detected short pulses correspond to the beginning of the frame.
Claim 9
Dependent Claim
138 words
Apparatus for synchronizing a programmable sync generator with an external video signal comprising: a start circuit coupled to the video signal for furnishing a start pulse to the sync generator at the beginning of a frame to initially synchronize the sync generator output signal with the video signal, the start circuit comprising a sync separator for digitizing the video signal to obtain a composite sync signal, and a circuit for monitoring the width of the composite sync signal pulses to detect the start of a frame; a phase locked loop for maintaining synchronism including the sync generator, a voltage controlled oscillator coupled to the sync generator clock input, and a phase comparator; and the phase comparator being responsive to the video signal and the generator output and includes means for producing a voltage for controlling the oscillator frequency.
Claim 10
Dependent Claim
138 words
Apparatus for synchronizing a programmable sync generator with an external video signal comprising: a start circuit coupled to the video signal for furnishing a start pulse to the sync generator at the beginning of a frame to initially synchronize the sync generator output signal with the video signal, the start circuit comprising a sync separator for digitizing the video signal to obtain a composite sync signal, and a circuit for monitoring the width of the composite sync signal pulses to detect the start of a frame; a phase locked loop for maintaining synchronism including the sync generator, a voltage controlled oscillator coupled to the sync generator clock input, and a phase comparator; and the phase comparator being responsive to the video signal and the generator output and includes means for producing a voltage for controlling the oscillator frequency.
Claim 11
Dependent Claim
155 words
Apparatus for synchronizing a programmable sync generator with an external video signal comprising: a start circuit coupled to the video signal for furnishing a start pulse to the sync generator at the beginning of a frame to initially synchronize the sync generator output signal with the video signal, the start circuit comprising a sync separator for digitizing the video signal to obtain composite and vertical sync signals and an odd/even field signal, and a circuit for monitoring the width of the composite sync signal pulses and the states of the vertical sync signal and the field signal for the start of a frame; a phase locked loop for maintaining synchronism including the sync generator, a voltage controlled oscillator coupled to the sync generator clock input, and a phase comparator; and the phase comparator being responsive to the video signal and the generator output and includes means for producing a voltage for controlling the oscillator frequency.
Claim 12
Dependent Claim
155 words
Apparatus for synchronizing a programmable sync generator with an external video signal comprising: a start circuit coupled to the video signal for furnishing a start pulse to the sync generator at the beginning of a frame to initially synchronize the sync generator output signal with the video signal, the start circuit comprising a sync separator for digitizing the video signal to obtain composite and vertical sync signals and an odd/even field signal, and a circuit for monitoring the width of the composite sync signal pulses and the states of the vertical sync signal and the field signal for the start of a frame; a phase locked loop for maintaining synchronism including the sync generator, a voltage controlled oscillator coupled to the sync generator clock input, and a phase comparator; and the phase comparator being responsive to the video signal and the generator output and includes means for producing a voltage for controlling the oscillator frequency.
Claim 13
Dependent Claim
205 words
Apparatus for synchronizing a programmable sync generator with an external video signal comprising: a start circuit coupled to the video signal for furnishing a start pulse to the sync generator at the beginning of a frame to initially synchronize the sync generator output signal with the video signal, the start circuit comprising a sync separator for digitizing the video signal to obtain composite and vertical sync signals and an odd/even field signal; and a circuit for detecting the start of a frame including a timer for generating a reference pulse width for each composite sync pulse, a circuit for comparing each composite sync pulse to a reference pulse to detect short pulses, the short pulses occurring at the beginning of each field, and a circuit for validating a short pulse as the start of a frame when it is coincident with vertical sync and field signals consistent with the start of a frame; a phase locked loop for maintaining synchronism including the sync generator, a voltage controlled oscillator coupled to the sync generator clock input, and a phase comparator; and the phase comparator being responsive to the video signal and the generator output and includes means for producing a voltage for controlling the oscillator frequency.
Claim 14
Dependent Claim
205 words
Apparatus for synchronizing a programmable sync generator with an external video signal comprising: a start circuit coupled to the video signal for furnishing a start pulse to the sync generator at the beginning of a frame to initially synchronize the sync generator output signal with the video signal, the start circuit comprising a sync separator for digitizing the video signal to obtain composite and vertical sync signals and an odd/even field signal; and a circuit for detecting the start of a frame including a timer for generating a reference pulse width for each composite sync pulse, a circuit for comparing each composite sync pulse to a reference pulse to detect short pulses, the short pulses occurring at the beginning of each field, and a circuit for validating a short pulse as the start of a frame when it is coincident with vertical sync and field signals consistent with the start of a frame; a phase locked loop for maintaining synchronism including the sync generator, a voltage controlled oscillator coupled to the sync generator clock input, and a phase comparator; and the phase comparator being responsive to the video signal and the generator output and includes means for producing a voltage for controlling the oscillator frequency.
Claim 15
Dependent Claim
58 words
The invention as defined in claim 8 wherein the start of the frame is defined as the beginning of an odd field, and the validating circuit comprises: a logic circuit having the vertical sync and the odd/even field signals as inputs and producing an enabling output when the vertical sync is high and the field signal is low.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-05-04 | 2001-11-03 | 2002-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-04 | 2005-11-03 | 2006-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-04 | 2009-11-03 | 2010-05-05 | $7700.00 | Window Closed / Lapsed |