Automatic telephone answering system with a fail safe arrangement

Claim 1

An automatic telephone answering apparatus comprising a receiving circuit connected to telephone lines for detecting received signals, a signal sending and receiving circuit for picking up a caller''s information arriving through the telephone lines and giving forth the recorded reply, a magnetic recording and reproducing device for writing the information in a magnetic recording medium and reading out said information therefrom and a control device for controlling the aforesaid various operations, wherein said magnetic recording and reproducing devices consist of 1. an amplifier for amplifying signals representing the caller''s information an those representing the recorded reply, 2. a movable magnetic head for writing which generates magnetic flux according to the signals representing the caller''s information which were amplified by said amplifier, 3. an endless magnetic recording medium for allowing the recorded reply to be written in a prescribed track and the caller''s information to be written in other tracks by said movable magnetic head, 4. a fixed magnetic head for reading out the recorded reply recorded in the prescribed track of said endless magnetic recording medium, 5. a first rotation indicator and a second rotation indicator formed in the endless magnetic recording medium at a prescribed interval so as to detect its rotation, 6. a driving mechanism for shifting the movable magnetic head to the other tracks of the endless magnetic recording medium than the prescribed track when said medium completes a prescribed rotation, and 7. a motor for rotating the endless magnetic recording medium; and said control devices consists of 1. a first detector and a second detector so disposed as to face the first and second rotation indicators respectively of the endless magnetic recording medium and detect the rotation of said medium and form control signals, and 2. a control circuit for controlling rotating of the motor to cause the second detector to be aligned with the second rotation indicator when the automatic telephone answering apparatus is not in a waiting condition and allowing the motor naturally to cease to run when said apparatus is brought back to such waiting condition, and starting the motor upon arrival of signals and stopping the motor when the first and second detectors operate successively, thus resulting in the completion of a prescribed rotation of the magnetic medium. CM,2Elephone apparatus according to claim 1 wherein the control circuit comprises 1. a counter operated by outputs from the first and second detectors, 2. at least two semiconductors provided with a control electrode for starting or stopping the motor according to the outputs from said counter or its condition, that of said semiconductors which is used in starting the motor being supplied with a trigger signal from the receiving circuit, 3. a circuit for forming a trigger signal for the semiconductors provided with a control electrode according to outputs from said counter or its condition and outputs from the first or second detector in order to adjust the tape to the predetermined waiting position by controlling the operation of the motor, and 4. a readout gate and writing gate controlled according to outputs from said counter or its condition.