Measuring method and apparatus

• US 5,422,861 A
• Filed: 06/14/1993
• Issued: 06/06/1995
• Est. Priority Date: 09/01/1989
• Status: Expired due to Term

• Current Assignee: Quantronix Incorporated
• Original Assignee: Quantronix Incorporated
• Inventors: Kennington, Robert L., Stringer, Bradley J.
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US08/076,391
• Time in Patent Office: 722 Days
• Field of Search: 367/99, 364/564
• US Class Current: 367/99
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/04 specially adapted for measuring length or width of objects while moving
• CPC Class Codes: G01B 17/00 Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
• CPC Class Codes: G07B 2017/00685 Measuring the dimensions of mailpieces

Abstract

A method and apparatus for measuring the dimensions and determining the three-dimensional, spatial volume of objects. An object detection system is employed to detect proper placement of an object to be measured, and waveguides are employed as standoffs and received wave isolators for reflected-wave sensors. An autocalibration method for ultrasonic sensors is also disclosed.

Claims

1. An apparatus for measuring at least one dimension of an object, comprising:

an object support platen means;

a zero point on said object support platen means;

at least a first sensor means for determining a first dimension of said object between said first sensor means and said zero point;

object detection means to sense the presence at said zero point of an object to be measured and to generate a signal responsive to said presence; and

means responsive to said object detection means signal for enabling said at least first sensor means to determine at least said first dimension of said object.

2. The apparatus of claim 1, wherein said object support platen means is stationary, said apparatus further includes at least a second sensor means for determining a second dimension of said object between said second sensor means and said zero point, said first and second dimensions are mutually perpendicular, said apparatus includes object alignment means for alignment of substantially rectangular objects on said object support platen so that one corner of a said object may be placed at said zero point, and said enabling means enables both of said sensors responsive to said signal.

3. The apparatus of claim 1, wherein said object support platen means is linearly movable, said apparatus further includes at least a second sensor means for determining a second dimension of said object between said second sensor means and said zero point, said first and second dimensions are mutually perpendicular, said apparatus further includes means for aligning substantially rectangular objects to be measured so that one side of a said object is aligned with said linear movement of said object support platen means, said zero point is located in the line of travel of said aligned side of a said object, and said enabling means enables both of said sensors responsive to said signal.

4. The apparatus of claim 1, wherein said object detection means is isolated from said object support platen means.

5. The apparatus of claim 1, wherein said object detection means is located underneath said object support platen means.

6. The apparatus of claim 5, further including an aperture through said object support platen means proximate said zero point, and wherein said object detection means detects the presence of said object through said aperture.

7. The apparatus of claim 6, wherein said object detection means comprises a light emitter and a light receiver, both aimed through said aperture, and said object presence is detected through reflection of light from said object.

8. The apparatus of claim 7, wherein said light emitter and light receiver are at a location remote from said aperture, and further including a fiber optic cable associated with each of said light emitter and said light receiver for respectively transmitting light from said light emitter to said aperture and receiving said transmitted light reflected from an object covering said aperture.

9. The apparatus of claim 6, wherein said object detector means comprises switch means including probe means extending through said aperture.

10. The apparatus of claim 6, wherein said object detection means is adapted to measure changes in air pressure at said aperture attributable to the presence of a said object.

11. A method of obtaining a calibrated object dimension using an ultrasound sensor employed in dimensional measurement of said object, said method comprising:

providing a said ultrasound sensor a fixed, clear field distance from, and aimed toward, a zero point having a reflective surface substantially perpendicular to said direction of aim;

activating said ultrasound sensor to emit at least one ultrasonic wave pulse and receive said at least one emitted pulse after reflection from said reflective surface;

measuring a first travel time of said at least one ultrasonic wave pulse between emission and receipt by said ultrasound sensor;

inserting between said ultrasound sensor and said reflective surface an object having at least one known dimension adjacent said reflective surface with said at least one known dimension extending toward said ultrasound sensor and a side of said object closest to said ultrasound sensor substantially perpendicular to said direction of aim;

activating said ultrasound sensor to emit at least a second ultrasonic wave pulse and receive said at least one emitted pulse after reflection from said object side;

measuring a second travel time of at least said second ultrasonic wave pulse between emission and receipt by said ultrasound sensor;

subtracting said second travel time frown said first travel time;

dividing the remainder from said subtraction by said at least one known dimension;

dividing said first travel time by the result of said division operation to obtain said clear field distance;

periodically activating said ultrasound sensor into said clear field to emit additional ultrasonic wave pulses against said reflective surface, measuring the travel time between emission and receipt of each said wave by said ultrasound sensor; and

periodically dividing said periodic clear field travel time by said clear field distance to obtain a periodically updated time per dimensional unit calibration factor.

12. The method of claim 11, further including:

placing an object having an unknown dimension adjacent said reflective surface with said unknown dimension substantially perpendicular to said reflective surface between said reflective surface and said ultrasound sensor;

activating said ultrasound sensor to emit at least one ultrasonic wave pulse and receive said at least one emitted pulse after reflection from said object of said unknown dimension;

measuring the travel time of said at least one ultrasonic wave pulse between emission, reflection from said object of unknown dimension and receipt by said ultrasound sensor;

dividing said travel time of said wave reflected from said object of unknown dimension by said time per dimensional unit calibration factor to obtain the distance between said sensor and said object of said unknown dimension; and

subtracting said sensor to object of unknown dimension distance from said clear field distance to obtain said unknown dimension.

13. An apparatus for measuring at least one dimension of an object through the use of at least one reflected wave sensor, comprising:

an object support platen means;

a said at least one reflected wave sensor aimed toward a target location on said object support platen means;

object detection means between said at least one sensor and said target location to sense the presence of a said object at an undesired location in too close a proximity to said at least one reflected wave sensor and to generate a signal responsive to said presence; and

means responsive to said object detection means signal for disabling said at least one reflected-wave sensor.

14. The apparatus of claim 13, wherein said object detection means comprises a paired light emitter and light receiver, the latter for detecting light emitted by the former and reflected from said object at said undesired location in too close a proximity to said at least one sensor.

15. The apparatus of claim 14, wherein said light emitter and said light receiver are each remote from said location, and further including fiber optic cables for transmitting said light to said undesired location from said remote light emitter and from said location to said light receiver.