Sensor for measuring a movement characteristic of an object

• US 5,648,657 A
• Filed: 02/06/1996
• Issued: 07/15/1997
• Est. Priority Date: 02/06/1996
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Motor Company
• Inventors: Sundararajan, Srinivasan, Przybylo, Karin H., Teevens, Jerome P.
• Primary Examiner(s): Le, Que
• Application Number:
  US08/597,136
• Time in Patent Office: 525 Days
• Field of Search: 250/231.1, 250/223 R, 250/231.18, 250/559.32, 356/28, 73/11.02, 73/11.03, 73/12.04, 73/488, 73/490-493, 340/436, 340/441, 340/669-670, 180/275, 180/279, 180/280-282, 180/169, 280/728.1, 280/734-735
• US Class Current: 250/231.1
• CPC Class Codes: G01D 5/34746 Linear encoders

Abstract

A sensor for measuring a movement characteristic of an object has a housing, an emitter emitting electromagnetic radiation, a detector for receiving electromagnetic radiation, a rod having a graduated scale with a plurality of first regions and second regions for reflecting the electromagnetic radiation from the emitter. A plurality of rollers positions the rod within the housing. As the object moves the first and second regions, the emitter and detector reflect different levels of electromagnetic radiation. The detector generates an output voltage corresponding the level of reflected radiation from the scale. The output voltage is then converted into displacement, velocity, or acceleration.

Claims

1. An apparatus for measuring a characteristic of movement of an object comprising:

an emitter emitting electromagnetic radiation;

a rod having a graduated scale with a plurality of first regions and second regions for reflecting electromagnetic radiation from said emitter, said first regions and said second regions reflecting different levels of electromagnetic radiation, said rod having a contact surface for operatively contacting said object;

a detector for receiving said electromagnetic radiation directed at said scale, said detector generating an output voltage corresponding to the level of reflected radiation from said scale.

2. An apparatus as recited in claim 1 further comprising a circuit for converting said output voltage o into a displacement of said object.

3. An apparatus as recited in claim 1 further comprising a circuit for converting said output voltage into a velocity of said object.

4. An apparatus as recited in claim 1 further comprising a circuit for converting said output voltage into an acceleration of said object.

5. An apparatus as recited in claim 1 wherein said radiation comprises light.

6. An apparatus as recited in claim 1 wherein said light comprises a wavelength of infra-red.

7. An apparatus as recited in claim 1 wherein said first and second regions are equally sized.

8. An apparatus for measuring a characteristic of movement of an object comprising:

a housing;

an emitter emitting electromagnetic radiation;

a rod having a graduated scale with a plurality of first regions and second regions for reflecting electromagnetic radiation from said emitter, said first regions and said second regions reflecting different levels of electromagnetic radiation, said rod having a contact surface for operatively contacting said object;

guide means for slidably positioning said scale within said housing; and

a detector for receiving said electromagnetic radiation directed at said scale, said detector generating an output voltage corresponding to the level of reflected radiation from said scale.

9. An apparatus as recited in claim 8 further comprising a circuit for converting said output voltage into a displacement of said object.

10. An apparatus as recited in claim 8 further comprising a circuit for converting said output voltage into a velocity of said object.

11. An apparatus as recited in claim 8 further comprising a circuit for converting said output voltage into an acceleration of said object.

12. An apparatus as recited in claim 8 wherein said radiation comprises light having a wavelength of infra-red.

13. An apparatus as recited in claim 8 wherein said guide means comprises a plurality of rollers.

14. An apparatus as recited in claim 8 wherein said first and second regions are equally sized.

15. An apparatus as recited in claim 8 wherein said rollers provide a resistance to movement of said rod.

16. A method for determining a characteristic of movement of an object comprising the steps of:

providing a rod having a graduated scale, said rod having a contact surface for operatively contacting said object;

extending rod partially out of said housing;

positioning said contact surface against said object;

emitting electromagnetic radiation to reflect from said graduated scale;

receiving the reflected electromagnetic radiation; and

generating an output voltage proportional to said received electromagnetic radiation;

converting said output voltage into a characteristic of movement of the object.

17. A method as recited in claim 16 wherein said characteristic is displacement.

18. A method as recited in claim 16 wherein said characteristic is velocity.

19. A method as recited in claim 16 wherein said characteristic is acceleration.

20. A method as recited in claim 16 wherein said radiation comprises light having comprises a wavelength of about infra-red.