Thermal imager having sunlight exposure protection mechanism

• US 7,484,885 B1
• Filed: 06/30/2004
• Issued: 02/03/2009
• Est. Priority Date: 06/30/2004
• Status: Expired due to Fees

• Current Assignee: Raytek Corporation (Fortive Corp.)
• Original Assignee: Raytek Corporation (Fortive Corp.)
• Inventors: Heinke, Thomas, Carlson, Paul S.
• Primary Examiner(s): VERBITSKY, GAIL KAPLAN
• Application Number:
  US10/881,710
• Time in Patent Office: 1,679 Days
• Field of Search: 374/120, 374/121, 374130-133, 374/208, 250/338.1, 356/43, 356/51, 396/448
• US Class Current: 374/132
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/02 Constructional details
• CPC Class Codes: G01J 5/025 Interfacing a pyrometer to an external device or network; User interface
• CPC Class Codes: G01J 5/026 Control of working procedures of a pyrometer, other than calibration; Bandwidth calculation; Gain control
• CPC Class Codes: G01J 5/0265 Handheld, portable ear thermometers G01J5/049
• CPC Class Codes: G01J 5/07 Arrangements for adjusting the solid angle of collected radiation, e.g. adjusting or orienting field of view, tracking position or encoding angular position optical collimating elements G01J5/0806
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0804 Shutters
• CPC Class Codes: G01J 5/10 using electric radiation detectors
• CPC Class Codes: H04N 23/50 Constructional details
• CPC Class Codes: H04N 23/633 for displaying additional information relating to control or operation of the camera
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A thermal imaging apparatus comprises a housing defining an entrance pupil for ingress of imaging radiation. At least one light sensor is positioned forward of the entrance pupil. An electronic imaging device such as a focal plane array is located in the housing rearward of the entrance pupil for converting imaging radiation to electrical signals for further processing. The apparatus further includes a shutter having an open position and a closed position. In the closed position, the shutter is located between the entrance pupil and the electronic imaging device so as to inhibit exposure of the electronic imaging device to incident radiation. Circuitry is provided for selectively operating the shutter to be in the closed position based on signals produced at the light sensor.

Claims

1. A hand-held thermal imaging apparatus comprising:

a housing defining an entrance pupil for ingress of imaging radiation;

at least one light sensor positioned forward of said entrance pupil;

an electronic imaging device located in said housing rearward of said entrance pupil for converting said imaging radiation to electrical signals for further processing;

a display located on said housing for showing thermal images detected by said electronic imaging device;

a mechanical shutter having an open position and a closed position, wherein said shutter is located between said entrance pupil and said electronic imaging device in said closed position so as to inhibit exposure of said electronic imaging device to incident radiation; and

circuitry for selectively operating said shutter to be in said closed position based on signals produced at said light sensor when incident radiation that would otherwise impinge said electronic imaging device exceeds a predetermined threshold.

2. A thermal imaging apparatus as set forth in claim 1, wherein said electronic imaging device is a focal plane array.

3. A thermal imaging apparatus as set forth in claim 2, wherein said focal plane array is an infrared focal plane array.

4. A thermal imaging apparatus as set forth in claim 1, wherein said light sensor is located in a portion of said housing forward of said entrance pupil forming a hood.

5. A thermal imaging apparatus as set forth in claim 4, wherein said light sensor is situated at a position in said hood below and forward of said entrance pupil.

6. A thermal imaging apparatus as set forth in claim 4, wherein said light sensor is situated at a position in said hood to detect sun exposure before imaging thereof by said electronic imaging device.

7. A thermal imaging apparatus as set forth in claim 4, wherein said light sensor comprises a silicon phototransistor.

8. A thermal imaging apparatus as set forth in claim 4, wherein said light sensor comprises a pair of light sensors.

9. A thermal imaging apparatus as set forth in claim 8, wherein said pair of light sensors are located at respective left and right positions below and forward of said entrance pupil.

10. A thermal imaging apparatus as set forth in claim 1, further comprising a lens cap adapted to cover said entrance pupil when said apparatus is not in use.

11. A thermal imaging apparatus as set forth in claim 10, wherein said apparatus is adapted to be in a powered off state when said lens cap in position to cover said entrance pupil.

12. A thermal imaging apparatus as set forth in claim 11, wherein a power switch is closed when said lens cap is not in position covering said entrance pupil.

13. A thermal imaging apparatus as set forth in claim 12, wherein said power switch is opened by a magnet carried by said lens cap.

14. A thermal imaging apparatus as set forth in claim 10, wherein said lens cap is slidable with respect to said housing.

15. An imaging apparatus comprising:

structure defining an entrance pupil for ingress of imaging radiation, said entrance pupil having a lens;

a focal plane array located rearward of said lens;

a mechanical shutter having an open position and a closed position, wherein said shutter is located between said lens and said focal plane array in said closed position so as to inhibit exposure of said focal plane array to incident radiation;

circuitry for selectively operating said shutter to be in a sun protection mode wherein said shutter is in said closed position when radiation that would otherwise impinge said focal plane array exceeds a predetermined threshold;

at least one light sensor located forward of said lens, said circuitry operative to control said shutter based on signals produced at said light sensor; and

a lens cap adapted to cover said entrance pupil when said apparatus is not in use, wherein said apparatus is adapted to be in a powered off state when said lens cap is in position to cover said entrance pupil.

16. An imaging apparatus as set forth in claim 15, further including a display on which a graphical representation is shown indicating that said imaging apparatus is in said sun protection mode.

17. An imaging apparatus as set forth in claim 15, wherein said shutter will remain in said sun protection mode until said apparatus is placed in said powered off state and subsequently placed in a powered on state.