Force-measuring apparatus including totalizer means

Claim 1

Weighing apparatus, comprising a. a stationary member including means defining a stationary magnetic field; b. a movable member normally having an initial no-load position relative to said stationary member; c. electromagnetic compensation means operable upon the application to said movable member of a weight to be measured for returning said movable member to said no-load position, said compensation means including 1. compensation coil means mounted on said movable member, and 2. means for supplying to said compensation coil direct-current pulses of constant height and of a length that corresponds with the instantaneous extent of displacement of said movable member from said no-load position, thereby to establish in said compensation coil means a restoring magnetic field relative to said stationary magnetic field, said pulse supplying means including a. position detecting means for generating a displacement signal the magnitude of which corresponds with the extent of displacement of the movable member from the no-load position; b. means including an oscillator and a first frequency divider for generating a sawtooth voltage of a relatively high frequency; c. means including normally-open switch means operable to connect a source of direct current with said compensation coil; and d. pulse length modulator means for periodically closing said switch means for periods of time that correspond with the magnitude of said displacement voltage relative to the instantaneous magnitude of said sawtooth voltage; d. pulse counter means; e. gate means operable by said pulse length modulator means for supplying counting pulses from said oscillator to said counter means during the periods of time said switch means is closed by said pulse length modulator, whereby said counter means continuously totalizes said pulses; f. counter pulse storage and display means; and g. means for periodically transferring to said storage and display means the instantaneous totalized value of the pulses in said counter means, said transfer means including 1. second frequency divider means connected with said first frequency divider means for producing transfer pulses of a relatively low frequency, and 2. counter control means operable by said low frequency transfer pulses for transferring the totalized condition of said counter means to said storage and display means and for resetting said counter to zero.