Television interrupt circuit
First Claim
1. An apparatus for use in a television having an audio demodulator for producing at its output an electrical audio signal normally corresponding to a sound program in a television signal, a cathode ray tube for producing a video picture in response to a video signal and an audio speaker for producing television sound in response to the audio signal, comprising:
- a detector for being connected to the output of the audio demodulator to receive the electrical audio signal and for producing a detect signal when the electrical audio signal does not correspond to a sound program; and
disable means for interrupting at least a portion of the television signal that produces the video picture in response to the detect signal.
1 Assignment
0 Petitions
Accused Products
Abstract
An interrupt circuit monitors a television audio demodulator or an external video input circuit and interrupts the video signal to CRT and the audio signal to television speaker(s) whenever a lost signal condition is detected. In the preferred embodiment, a lost signal condition is detected by monitoring the voltage level of the signal from the audio demodulator or the external video input circuit and generating a detect signal whenever the voltage exceeds a predetermined threshold. When a television signal is lost, both the audio demodulator signal and the external video signal constitute a noise signal that has a voltage amplitude that is greater than the normal operating range of either of these two signals. In the preferred embodiment, when a detect signal is produced, both the video signal to the CRT and the audio signal to the television speaker(s) are interrupted and alternate video and audio signals are provided to the CRT and speaker(s) by a microprocessor. These alternate signals will announce the lost signal condition to the viewer.
-
Citations
23 Claims
-
1. An apparatus for use in a television having an audio demodulator for producing at its output an electrical audio signal normally corresponding to a sound program in a television signal, a cathode ray tube for producing a video picture in response to a video signal and an audio speaker for producing television sound in response to the audio signal, comprising:
-
a detector for being connected to the output of the audio demodulator to receive the electrical audio signal and for producing a detect signal when the electrical audio signal does not correspond to a sound program; and disable means for interrupting at least a portion of the television signal that produces the video picture in response to the detect signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. An apparatus for use in a television having a video input circuit for receiving an input video signal normally corresponding to a video program in a television signal and for producing a second video signal corresponding to the input video signal, the second video signal being amplified with respect to the input video signal, being within a predetermined range of amplitudes when a valid input video signal is received and being amplified above the predetermined range when the input video signal of the television signal is lost, a cathode ray tube for producing a video picture in response to the second video signal and an audio speaker for producing television sound in response to an audio signal, comprising:
-
a detector for being connected to the video input circuit to receive the second video signal and for producing a detect signal in response to the second video signal exceeding the predetermined range when the input video signal is lost; and disable means for interrupting at least a portion of the television signal in response to the detect signal. - View Dependent Claims (14)
-
-
10. An apparatus for use in a television having a video circuit for receiving a video input signal normally corresponding to a video program in a television signal, a cathode ray tube for producing a video picture in response to a video signal and an audio speaker for producing television sound in response to an audio signal, comprising:
-
a detector for being connected to the video input circuit to receive the input signal and for producing a detect signal when the input signal does not correspond to a video program; disable means for interrupting at least a portion of the television signal in response to the detect signal; and said detector comprising a noise detector that is operable to detect noise at the video input circuit to thereby determine that the input signal does not correspond to a video program and to produce the detect signal when the noise is detected. - View Dependent Claims (11, 12, 13)
-
-
15. An apparatus for use in a television having an audio demodulator for producing at its output an electrical audio signal normally corresponding to a television sound program, a video input circuit for receiving an input signal normally corresponding to a television video program, a cathode ray tube for producing a video picture in response to a video signal and an audio speaker for producing television sound in response to the electrical audio signal, comprising:
-
a switch having a first input for being connected to receive the electrical audio signal of the audio demodulator, a second input for being connected to receive the input signal of the video input circuit and having an output, said switch being operable to selectively apply one of its input signals to its output; a detector connected to the output of said switch for producing a detect signal when the signal at said output is not a valid audio or video signal; picture disable means for interrupting the video signal to cathode ray tube in response to the detect signal; and sound disable means for interrupting the audio signal to speaker in response to the detect signal. - View Dependent Claims (16, 17, 18, 19, 20, 21)
-
-
22. In a television apparatus having first means for producing an electrical audio signal normally corresponding to a sound program in a television signal, said audio signal exceeding a predetermined amplitude range when the sound program is lost, display means for producing a video picture in response to a video signal and speaker means for producing television sound in response to the audio signal, the improvement comprising:
-
detector means connected to said first means for receiving said electrical audio signal and for producing a detect signal in response to the audio signal exceeding the predetermined amplitude range when the sound program is lost and said electrical audio signal corresponds to a loss of the sound program; and disable means connected to receive said detect signal for interrupting at least a selected one of said video picture and said television sound in response to said detect signal. - View Dependent Claims (23)
-
Specification