Sony Corporation

Sony Electronics Inc

Steve Edwards

Mehrdad Nayebi

Duc Hongle Ngo

Duc Trong Ngo

A video/graphics overlay integrated circuit receives an analog composite video signal and a digital composite video signal and combines them in a predetermined format into an output composite video signal which is transmitted to a display device such as a television set. The digital video signal may be comprised of digital video, graphics data or a combination of digital video and graphics data. The digital video and graphics data are encoded by a digital encoder integrated circuit into a digital composite video signal. The digital composite video signal is coupled to the video/graphics overlay integrated circuit. An automatic phase correction circuit detects any phase difference between the burst signals of the analog composite video signal and the digital composite video signal. A phase control signal is generated by the automatic phase correction circuit and used to correct the phase and frequency of the digital composite video signal and ensure that it corresponds to the phase and frequency of the analog composite video signal. The automatic phase correction circuit uses the analog composite video signal as the master and adjusts the phase and frequency of the digital composite video signal until they are locked to the phase and frequency of the analog composite video signal. A numerically controlled oscillator generates an appropriate oscillating sinusoidal signal representing a burst frequency signal within the digital composite video signal. The phase and frequency of the oscillating sinusoidal signal are appropriately monitored and adjusted to correspond with the phase and frequency of the analog composite video signal.

Automatic phase control apparatus for phase locking the chroma burst of

A video/graphics overlay circuit receives an analog input composite video signal and a digital input composite video signal and combines them into a linear combination output composite video signal depending on the state of one or more mixer control signals. The two composite video input signals are each capacitively coupled to buffer and clamp circuits through which the blank or DC level of each signal is clamped to two volts. The outputs of the buffer and clamp circuits are then fed to a mixer circuit and burst separator circuits. The mixer circuit generates the output composite video signal which is a linear combination of the input composite video signals as controlled by the one or more mixer control signals. The burst separator circuits separate the burst signal from the input composite video signals. The extracted burst signals are then provided to a burst signal phase-locked loop for locking the burst signals of the input composite video signals in phase. The feedback loop of the burst signal phase-locked loop is closed through a digital encoder circuit and changes the phase and frequency of the burst signal within the digital input composite video signal until it is locked in phase with the analog input composite video signal. A burst lock signal is generated when the burst signals of the two input signals are locked in phase. A horizontal lock signal is generated when the horizontal sync signals of the two input signals are locked in phase. A black and white detector circuit generates a signal which indicates whether the analog input composite video signal is a black and white signal or a color signal.

Video overlay circuit for synchronizing and combining analog and digital

A mixer control circuit generates content control signals which are used by a mixer circuit to control the content of an output signal. The output signal will include either an analog signal, a digital signal or a mixture of the analog and digital signals. The level of a digital content control signal corresponds to the percentage of the output signal which includes the digital signal. The level of an analog content control signal corresponds to the percentage of the output signal which includes the analog signal. When the output signal includes a mixture of the analog and digital signals, a differential pair and an external control voltage are used to specify the percentage of each signal to be included within the output signal. During a horizontal blanking period, when the signals are being mixed, the differential pair and the external control voltage are bypassed and only the analog signal is included within the output signal. When the output signal is to include only one of the signals, either analog or digital, the differential pair and the external control voltage are also bypassed. A switching network is used to control the generation of the content control signals. The switching network is controlled by a control logic circuit in response to the levels of two control signals and a horizontal blanking signal.

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San Jose, CA, United States of America

Steve Edwards