1. Field of the Invention
This invention relates generally to noise generating toys, and more particularly, to an optical differential sensing circuit for actuating a noise generator in a toy to emit at least one, and preferably plural, audible sounds.
2. Description of the Prior Art
Children have in the past exhibited a desire to play with toys that mimic behavior typical of a real-life human or animal. The advancement of the electronics industry has made it possible for toys to more realistically portray the desired traits. In particular, toys which are capable of producing audible sounds upon activation by the user have in the past proven to be very successful.
Initially, noise-generating toys were manually activated by a user depressing various portions of the toy to force air through whistle or reed-type mechanisms. However, these manually actuated mechanisms failed to closely mimic or emit sounds which were typical of the human or animal which the toy portrayed. Further, this type of prior art had to be directly activated by the user and could not be sustained over any length of time.
Electronic circuits were adapted to electrically control movement of toys and the audible sounds emitted therefrom. For example, U.S. Pat. No. 3,443,338 to Collins discloses a toy which simultaneously mimics a dog's physical movements while emitting an audible sound which imitates a dog's bark. The mechanism for eliciting the simulated dog movements and barks is directly activated by a switch controlled by the user.
The development of the photo-cell enabled manufacturers to provide toys which could be activated remotely. For example, U.S. Pat. No. 3,274,729 to Refabert discloses a doll having a photo-cell actuated sounding means. In particular, the Refabert patent teaches a photo conductive cell which is mounted in such a manner on the doll so that it can be irradiated by light, such as on the doll's chest or in one of the doll's eyes. A small electric motor is energized under control of the intensity of the irradiation of the photo conductive cell. Means for producing an audible signal is operated by the small electric motor. The means for producing the audible sound comprises at least one bellow and reed, which mechanically create the audible sound.
As electrical technology has advanced, the need existed to provide remotely actuated toys which elicit a plurality of audible sounds without the need for providing plural mechanical bellows and reed combinations. Recently, the tendency has been to provide verbally actuated toys. For example, U.S. Pat. No. 4,221,927 to Dankman et al discloses a voice responsive talking toy. The Dankman patent discloses a toy which, in response to a complex sound such as human speech, generates a train of audio pulses. The pulses generated by the Dankman toy are psuedo-random with respect to frequency composition and duration. Such toys require fairly complex and expensive electrical circuits.
The need still exists to provide a toy which is remotely or automatically actuated to emit audible sounds and which is efficiently and inexpensively manufactured.