Information retrieval system having ramp motor control

In an information retrieval system of the type which locates preselected information bearing elements for inspection, wherein the information bearing elements are consecutively numbered for identification and wherein the system includes a register for storing the identification number of the selected information bearing element to be inspected as a target number, a sensor for sensing the information bearing elements, and a counter for providing the identification number of the information bearing element currently being sensed as a current number, a new and improved scanning means for locating a preselected information bearing element comprising:

• a comparator coupled to the register and to the counter for comparing the current number to the target number and for providing responsive to said comparison a first signal when the target number is greater than the current number, and a second signal when the target number is less than the current number;
• a ramp generator for providing a ramp voltage;
• first drive means coupled to said ramp generator for driving the information bearing elements at a rate proportional to the magnitude of said ramp votage;
• second drive means for driving the information bearing elements at a substantially fixed rate;
• drive direction control means associated with said first and second drive means and responsive to said first and second signals for driving the information bearing elements in a first direction responsive to said first signal and a second direction responsive to said second signal;
• drive selection means coupled to said ramp generator and to said second drive means for actuating said second drive means responsive to a preselected ramp voltage level;
• detecting means coupled to said comparator and responsive to a change in the levels of said first and second signals for providing a control voltage;
• ramp generator reset means coupled to said detecting means and to said ramp generator for resetting said ramp generator responsive to said control signal;
• and
• disabling means coupled to the sensor for detecting when the preselected information bearing element is aligned with the sensor for a predetermined period of time to thereby detect when the preselected information bearing element has been located and for disabling said ramp generator responsive to such detection.

In an information retrieval system of the type for use with film having a plurality of information bearing elements in the form of image frames, wherein the image frames are consecutively numbered for identification with each frame being associated with an identifiable marker, and wherein the system includes a register for storing the identification number of a selected frame to be inspected as a target number, a sensor for sensing the markers, and a counter for providing the identification number of the frame currently being sensed as a current number, a new and improved scanning means for locating a preselected image frame for inspection comprising:

• a first comparator coupled to the register and to the counter for comparing the current number to the target number and for providing to said comparison a first signal when the target number is greater than the current number, and a second signal when the target number is less than the current number;
• a ramp generator for providing a ramp voltage;
• a D.C. motor coupled to said ramp generator for driving the film at a rate substantially proportional to the magnitude of said ramp voltage;
• an A.C. motor for driving the film at a substantially fixed rate;
• first and second clutches selectively engageable with said D.C. and A.C. motors responsive to said first and second signals to cause the film to be driven in a first direction responsive to said first signal and a second direction responsive to said second signal;
• a second comparator having a first input coupled to a reference voltage having a preselected magnitude, a second input coupled to said ramp generator;
• and an output coupled to said A.C. motor for activating said A.C. motor when said ramp voltage equals said preselected magnitude;
• detecting means coupled to said first comparator and responsive to a change in the levels of said first and second signals for providing a control signal;
• ramp generator reset means coupled to said detecting means and to said ramp generator for resetting said ramp generator responsive to said control signal;
• and
• disabling means coupled to the sensor for detecting when the marker of the preselected image frame is aligned with the sensor for a predetermined period of time to thereby detect when the preselected image frame has been located and for disabling said ramp generator responsive to such detection.