Thermal emitted radiation detecting device

• US 5,668,539 A
• Filed: 02/16/1996
• Issued: 09/16/1997
• Est. Priority Date: 08/30/1995
• Status: Expired due to Fees

• Current Assignee: 1138037 Ontario Limited
• Original Assignee: 1138037 Ontario Limited
• Inventors: Patchell, John W.
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): GOINS, DAVETTA WOODS
• Application Number:
  US08/602,467
• Time in Patent Office: 578 Days
• Field of Search: 340/903, 340/435, 340/436, 340/567, 340/904, 340/905, 340/961, 340/968, 356/349, 250/349
• US Class Current: 340/903
• CPC Class Codes: B60Q 1/52 for indicating emergencies
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• CPC Class Codes: B60R 2011/0003 inside the vehicle
• CPC Class Codes: B60R 2011/0033 Rear-view mirrors
• CPC Class Codes: G01J 5/0022 for sensing the radiation of moving bodies
• CPC Class Codes: G01S 3/785 using adjustment of orientation of directivity characteristics of a detector or detector system to give a desired condition of signal derived from that detector or detector system
• CPC Class Codes: G08G 1/16 Anti-collision systems road vehicle drive control systems for predicting or avoiding probable or impending collision otherwise than by control of a particular sub-unit B60W30/08
• CPC Class Codes: G08G 1/167 Driving aids for lane monitoring, lane changing, e.g. blind spot detection

Abstract

A thermal emitted radiation detecting device is configured to detect objects in visual blind spots of a vehicle. A low cost differential detector is used which is sensitive to temperature change. Optics train two different fields of view on the detector and switch between the two fields of view to provide a blind spot field of view and a reference field of view. The presence of a vehicle in the blind spot field of view results in a temperature difference between the two fields of view. The resulting detector output signal is compared to predetermined threshold levels and then used to provide an indication, either visual or audible. Several embodiments of optics and switching fields of view are provided.

Claims

1. A thermal emitted radiation detecting device for detecting objects in a blind spot comprising:

detector means for generating an output signal responsive to thermal emitted radiation;

means for defining first and second fields of view relative to the detector means;

means for switching the field of view detected to generate a combined output signal; and

means for deriving an indication of a proximate object from the combined output signal, whereby the first field of view comprises the blind spot and the second field of view comprises a reference field and switching between the first and second fields generates a difference in thermal emitted radiation at the detector means when the proximate object is in the first field of view.

2. A device as claimed in claim 1 wherein the detector means comprises a differential thermal emitted radiation detector.

3. A device as claimed in claim 2 wherein said means for defining first and second fields of view comprise optics having first and second optical elements.

4. A device as claimed in claim 3 wherein said first and second optical elements are Fresnel lenses.

5. A device as claimed in claim 3 wherein said first and second optical elements are concave mirrors.

6. A device as claimed in claim 2 wherein said means for defining first and second fields of view comprise optics having a single optical element capable of movement between a first position and a second position corresponding to respective first and second fields of view.

7. A device as claimed in claim 6 wherein the optical element is Fresnel lens.

8. A device as claimed in claim 6 wherein the optical element is concave mirror.

9. A device as claimed in claim 6 wherein the optical element is a planar mirror and the optics further comprise a fixed optical element.

10. A device as claimed in claim 9 wherein the fixed optical element is Fresnel lens.

11. A device as claimed in claim 9 wherein the fixed optical element is concave mirror.

12. A device as claimed in claim 3 wherein said means of switching comprises a shutter operable between first and second positions corresponding to allowing respective first and second fields of view to be detected.

13. A device as claimed in claim 12 wherein the shutter includes an opaque panel pivotally disposed between the detector and the optics, a spring biasing the panel to the first position and an electromagnet for attracting the panel to second position.

14. A device as claimed in claim 12 wherein the shutter includes a resilient reed disposed between the detector and the optics and an electromagnet for causing the reed to vibrate at a predetermined frequency.

15. A device as claimed in claim 12 wherein the shutter includes a rotary blade disposed between the detector and the optics.

16. A device as claimed in claim 6 wherein said means of switching comprises a vibrator for effecting movement of the optics between first and second positions corresponding to allowing respective first and second fields of view to be detected.

17. A device as claimed in claim 16 wherein the vibrator is a piezoelectric device.

18. A device as claimed in claim 16 wherein the vibrator is an electromechanical device.

19. A device as claimed in claim 1 wherein the means for detecting comprises first and second proportional detectors and wherein said first and second fields of view relate respectively thereto.

20. A device as claimed in claim 19 wherein the means for switching comprises an electrical switch for switching between the outputs of said first and second detectors.

21. A device as claimed in claim 1 wherein said means for deriving an indication includes a high-pass filter.

22. A device as claimed in claim 21 wherein the means for deriving includes an amplifier.

23. A device as claimed in claim 22 wherein the means for deriving includes a demodulator operable at a predetermined frequency corresponding to the frequency of operating the means for switching.

25. A device as claimed in claim 3 wherein the means for switching includes a square wave generator of predetermined frequency.

26. A device as claimed in claim 6 wherein the means for switching includes a square wave generator of predetermined frequency.

27. A device as claimed in claim 6 wherein the means for switching includes a saw-tooth wave generator of predetermined frequency.

24. A device as claimed in 23 wherein the means for deriving includes and annunciator.

28. A thermal emitted radiation detecting device for detecting objects in a blind spot comprising:

a detector responsive to changes in thermal emitted radiation received to generate an output signal;

optics for defining first and second fields of view relative to the detector;

a shutter for switching the field of view detected to generate a combined output signal;

a signal generator for providing a square wave of predetermined frequency for operating the shutter;

a high-pass filter connected to the detector for filtering the combined output signal;

a demodulator connected to the high-pass filter and the signal generator for deriving an object event signal; and

an annunciator for comparing the object event signal to predetermined thresholds and providing an indication of the presence of an object in the blind spot, whereby the first field of view comprises the blind spot and the second field of view comprises a reference field and switching between the first and second fields generates a difference in thermal emitted radiation at the detector means when the proximate object is in the first field of view.