Patent Document ID: 4532648
Application ID: 06428230

Base Claim:
1. A speech recognition system for an automotive vehicle for recording or recognizing a spoken instruction received through a microphone and for activating a vehicle actuator in response to a recognized spoken instruction, which comprises: (a) means for detecting whether or not an automotive vehicle engine is operating and outputting one of an engine operating signal and an engine stopped signal; (b) a speech input and voice detection section connected to the microphone for amplifying a spoken instruction signal transduced through the microphone, detecting the start and end of a spoken instruction, and outputting an instruction start command signal and an instruction end command signal, respectively, in response to detection thereof, at least one of the gain factor in said speech input section and the threshold level in said voice detection section being so adjusted that the sensitivity to spoken instructions can be reduced and that the driver must necessarily utter a spoken instruction in a louder voice to reduce the proportion of noise level to spoken instruction signal level, when said engine operation detecting means outputs said engine operating signal; and (c) a voice analysis section connected to said speech input and voice detection section and responsive to instruction start and instruction end command signals for analyzing the spoken instruction signal from said speech input section, comparing the results of analysis with predetermined reference values corresponding to at least one spoken instruction, and activating at least one actuator when the results of analysis match predetermined reference values associated with the actuator.

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Claim 7:
7. A speech recognition system for an automotive vehicle as set forth in claim 1, wherein said voice detection section comprises: (a) a first smoother connected to said speech input section for smoothing the spoken instruction signal amplified via said speech input section; (b) a second smoother connected to said speech input section for smoothing the spoken instruction signal amplified via said speech input section, the time constant of which is larger than that of said first smoother; (c) a first multiplier connected to said second smoother; (d) a second multiplier connected to said second smoother, the multiplication ratio of which is greater than that of said first multiplier; (e) an analog switch connected to said first multiplier for outputting the smoothed spoken instruction signal multiplied by said first multiplier in response to the engine stop signal from said engine operating detecting means and connected to said second multiplier for outputting the smoothed spoken instruction signal multiplied by said second multiplier in response to the engine operation signal from said engine operating detecting means; (f) a holding circuit connected to said analog switch for holding the smoothed spoken instruction signal passed through said analog switch as a reference threshold level in response to an instruction start command signal; (g) a voltage level comparator one input terminal of which is connected to said first smoother and the other input terminal of which is connected to said holding circuit, for comparing the spoken instruction signal voltage level smoothed by said first smoother with the reference threshold level outputted from said holding circuit and outputting a H-level signal when the signal voltage level smoothed by said first smoother exceeds the reference threshold level; and (h) a pulse duration comparator connected to said voltage level comparator for comparing the pulse width of the H-level signal from said level comparator with a reference start time and outputting a spoken instruction start command signal when the pulse width exceeds the reference start time and for comparing the pulse width of the L-level signal from said level comparator with a reference end time and outputting a spoken instruction end command signal when the pulse width exceeds the reference end, time, the spoken instruction start command signal being applied to said holding circuit as a holding signal.