Digital protractor

• US 20090038168A1
• Filed: 03/10/2008
• Published: 02/12/2009
• Est. Priority Date: 03/09/2007
• Status: Active Grant

• Current Assignee: Barry Douglas Wixey
• Original Assignee: Barry Douglas Wixey
• Inventors: Wixey, Barry Douglas
• Granted Patent: US 7,726,034 B2
• Time in Patent Office: Days
• US Class Current: 33/471
• CPC Class Codes: B43L 12/02 magnetic magnetic holding means for T-squares: B43L7/023
• CPC Class Codes: B43L 7/10 Plural straightedges relatively movable
• CPC Class Codes: G01B 3/563 Protractors for use in geodesy G01C1/00; protractor heads for drawing machines B43L13/08

Abstract

A digital protractor for measuring angular displacement from a referenced surface includes a substantially congruent pair of pivotally interconnected upper and lower arms, which arms are superposable upon one another. Each arm has a pair of substantially parallel engagement edges extending longitudinally of the arm. One of the arms is engagable along an engagement edge thereof with the reference surface. A capacitive sensor is secured to the lower arm and a digital readout device is secured to the upper arm for operatively cooperating with the capacitive sensor to measure and display the angular displacement from the arm engaging the reference surface to the other arm.

Claims

1. A digital protractor for measuring an angular displacement from a reference surface, said protractor comprising:

a substantially congruent pair of pivotally interconnected upper and lower arms, which arms are superposable upon one another, each arm having a pair of substantially parallel engagement edges extending longitudinally of said arm, one of said arms being engagable along an engagement edge thereof with the reference surface;

an electronic sensor secured to said lower arm; and

a digital readout device secured to said upper arm for operatively cooperating with said electronic sensor to measure and display the angular displacement from the arm engaging the reference surface to the other arm.

2. The device of claim 1 in which said digital readout includes a calibration switch that is engaged for said readout to display an angular displacement of zero degrees regardless of the angular displacement between said arms.

3. The device of claim 1 in which said arms comprise respective extruded components.

4. The device of claim 1 in which each engagement edge carries a magnetic element for adhering to a magnetically attracted material carried by the reference surface.

5. The device of claim 4 in which each engagement edge includes a longitudinal channel for receiving a respective magnetic element.

6. The device of claim 1 in which said sensor includes a capacitive sensor disk fixed to said lower arm and said readout includes a signal generating circuit attached to said upper arm for operatively cooperating with said capacitive sensor to measure an angular displacement between said arms and a display device connected to said signal generating circuit for displaying the measured angular displacement between said arms.

7. The device of claim 1 further including a locking apparatus for holding said arms together to maintain a selected angular displacement between said arms.

8. The device of claim 7 in which said arms are pivotally connected by a pivot pin and said locking apparatus includes a lock plate secured to said upper arm and having a locking engagement surface and central opening through which said pivot pin extends and a locking lever connected pivotally to said pin, and extending outwardly of said upper arm and carrying a bearing for interengaging said locking engagement surface of said lock plate when said lock lever is rotated about said pivot pin in a selected direction to tighten interengagement between said arms and hold said arms with a selected angular displacement therebetween.

9. The device of claim 8 in which said locking engagement surface includes a tapered groove formed in said locking plate and said bearing includes a ball bearing carried by said locking lever and received in said tapered groove whereby rotating said lever directs said ball bearing into a shallow portion of said groove to tighten interengagement between said upper and lower arms and hold said arms at the selected angular displacement.

10. The device of claim 6 in which said upper arm includes a longitudinal central channel for accommodating said signal generating circuit therein.

11. The device of claim 8 in which said sensor includes an annular disk disposed about said pivot pin for operatively cooperating with said digital readout.

12. The device of claim 6 in which said arms are connected by a pivot pin and said annular disk is disposed about said pin.

13. The device of claim 1 in which said upper and lower arms comprise a respective pair of superposable plates interconnected by a pivot pin that extends transversely through superposed, generally flat surfaces of said plates.

14. The device of claim 6 in which said annular disk and said signal generating circuit are enclosed by a housing from which said display is exposed.

15. The device of claim 13 in which said plates are pivotable relative to one another in a generally laminar manner with a substantially flat bottom surface of said upper arm being substantially parallel to an opposing flat top surface of said lower arm.

16. A digital protractor for measuring an angular displacement from a reference surface, said protractor comprising:

a pair of pivotally interconnected and generally planar upper and lower arms, which arms are superposable and pivotable in a laminar manner relative to one another, each arm having a pair of substantially parallel engagement edges extending longitudinally of said arm, one of said arms being engagable along an engagement edge thereof with the reference surface, at least one said engagement edge carrying a magnetic element for adhering to a magnetically attracted material carried by the reference surface;

an electronic sensor secured to said lower arm; and

a digital readout device secured to said upper arm for operatively cooperating with said electronic sensor to measure and display the angular displacement from the arm engaging the reference surface to the other arm.