Photometry device with correction for temperature change

• US 5,604,584 A
• Filed: 05/11/1995
• Issued: 02/18/1997
• Est. Priority Date: 06/23/1994
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Iwasaki, Hiroyuki
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/439,370
• Time in Patent Office: 649 Days
• Field of Search: 356/213, 356/215, 356/218, 356/221, 356/223, 356/226, 356/227, 356/229, 356/230, 356/243, 356/43, 356/44, 355/33, 355/30, 250/205, 250/238, 250/214 R, 250/214 C, 354/428, 354/464
• US Class Current: 356/218
• CPC Class Codes: G01J 1/42 using electric radiation detectors optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10

Abstract

A photometry device provides accurate photometry outputs over temperature by correcting light sensitivity variations of a light receiving element due to temperature variations. The photometry device includes the light receiving element, a light sensitivity detection device and a light sensitivity correction device. A correction formula is determined from the outputs of the light sensitivity corrections device generated at a standard condition and a condition other than the standard condition. The light sensitivity correction device corrects the outputs of the light receiving elements based on the correction formula.

Claims

1. A photometry device, comprising:

a light receiving element generating an output signal from light incident on a subject field, an amplitude of the output signal of the light receiving element corresponding to an intensity of the light from the subject field;

a light sensitivity detection device generating light sensitivity output data;

a temperature detection device generating a temperature value corresponding to a temperature of the light receiving element; and

a light sensitivity correction device correcting the amplitude of the output signal of the light receiving element for changes due to temperature variations of the light receiving element based on at least the light sensitivity output data generated by the light sensitivity detection device and an accurate temperature value, wherein the accurate temperature value is generated based on the temperature value and a set of temperature characteristic values of the temperature detection device stored in a memory device, the set of temperature characteristic values accounting for all temperature variations of the temperature detection device.

2. The photometry device of claim 2, wherein the temperature detection device comprises a thermistor circuit.

3. A photometry device, comprising:

a light receiving element generating an output signal from light incident on a subject field, an amplitude of the output signal of the light receiving element corresponding to an intensity of the light from the subject field;

a light sensitivity detection device generating light sensitivity output data;

a temperature detection device generating a temperature value corresponding to a temperature of the light receiving element; and

a light sensitivity correction device correcting the amplitude of the output signal of the light receiving element for changes due to temperature variations of the light receiving element based on at least the light sensitivity output data generated by the light sensitivity detection device and the temperature value generated by the temperature detection device, wherein the temperature detection device includes an optically shielded pixel element generating an output value that is related to the temperature of the light receiving element.

4. The photometry device of claim 3, wherein the light receiving element includes the light sensitivity detection device.

5. A photometry device, comprising:

a light receiving element generating an output signal from light incident on a subject field, an amplitude of the output signal of the light receiving element corresponding to an intensity of the light from the subject field;

a light sensitivity detection device generating light sensitivity output data; and

a light sensitivity correction device correcting the amplitude of the output signal of the light receiving element for changes due to temperature variations of the light receiving element based on at least the light sensitivity output data generated by the light sensitivity detection device, wherein the light sensitivity detection device includes;

a plurality of monitor pixels, each of the plurality of monitor pixels being disposed near the light receiving element so that a temperature of the plurality of monitor pixels is substantially a temperature of the light receiving element, each of the plurality of monitor pixels being injected with a predetermined amount of electric charge independent of an accumulation period, and

a microprocessor, the microprocessor correcting the amplitude of the output signal generated by the light receiving element based on outputs of the plurality of monitor pixels.

6. The photometry device of claim 5, wherein the light sensitivity detection device is a first monitor pixel and a second monitor pixel.

7. The photometry device of claim 6, wherein the microprocessor corrects the amplitude of the output signal based on a correction line, the correction line being determined by output values of the first and second monitor pixels for a predetermined standard condition and for conditions other than the standard condition, the correction line having an equation:

space="preserve" listing-type="equation">Vdata=(VO2-VO1)/(VO21-VO11)*Vdata'"'"'+(VO1*VO2'"'"'-VO1'"'"'*VO2)/(VO2'"'"'-Vo1'"'"'),

where VO1 and VO2 are outputs of the first and second monitor pixels for the standard condition, Vo1'"'"' and VO2'"'"' are outputs of the first and second monitor pixels for conditions other than the standard condition, Vdata and Vdata'"'"' are corrected and uncorrected output signal amplitudes, respectively.

8. The photometry device of claim 5, wherein the light receiving element comprises a plurality of light receiving pixels, each of the plurality of light receiving pixels comprising a plurality of spectral sensitivity regions, the microprocessor of the light sensitivity detection device correcting the amplitude of the output signal of the light receiving element for changes due to temperature variations for each of the plurality of spectral sensitivity regions of each of the plurality of light receiving pixels.

9. The photometry device of claim 8, wherein the microprocessor corrects the amplitude of the output signal for each of the plurality of spectral sensitivity regions by multiplying the output signal corresponding to each of the spectral sensitivity regions by a factor based on a predetermined relationship between a sensitivity of each of the plurality of spectral sensitivity regions and temperature.

10. The photometry device of claim 5, wherein the light receiving element includes the light sensitivity detection device.

11. A method for correcting an amplitude of a light receiving element output signal of a light receiving element for changes due to temperature, comprising:

determining correction formulas for the changes due to temperature of the light receiving element output signal amplitude based on at least outputs of a light sensitivity detection device;

determining a current temperature of the light receiving element using a set of temperature characteristic values of a temperature detection device stored in a memory device, the set of temperature characteristic values accounting for all temperature variations of the temperature detection device; and

correcting the amplitude of the light receiving element output signal based on at least the current temperature and the correction formulas.

12. The method of claim 11, wherein the current temperature is determined by a temperature detecting device comprising a thermistor circuit.

13. A method for correcting an amplitude of a light receiving element output signal for changes due to temperature, comprising:

determining correction formulas for the light receiving element output signal amplitude changes due to temperature based on at least outputs of a light sensitivity detection device;

determining a current temperature; and

correcting the amplitude of the light receiving element output signal at the current temperature based on at least the outputs of the light sensitivity detection device and the correction formulas, wherein the determining correction formulas step includes;

determining first output values of a plurality of monitor pixels at a standard temperature,

determining second output values of the plurality of monitor pixels at a temperature other than the standard temperature, and

generating a light sensitivity correction formula based on the first and second outputs of the plurality of monitor pixels.

14. The method of claim 13, wherein the plurality of monitor pixels comprises a first monitor pixel and a second monitor pixel and the light sensitivity correction formula comprises a correction line determined by outputs of the first and second monitor pixels for the standard temperature and for the temperature other than the standard temperature.

15. A method for correcting an amplitude of a light receiving element output signal for changes due to temperature, comprising:

determining correction formulas for the light receiving element output signal amplitude changes due to temperature based on at least outputs of a light sensitivity detection device;

determining a current temperature; and

correcting the amplitude of the light receiving element output signal at the current temperature based on at least the outputs of the light sensitivity detection device and the correction formulas, wherein the light receiving element comprises a plurality of spectral sensitivity regions and the output signal of the light receiving element comprises outputs of the plurality of spectral sensitivity regions, the determining correction formulas including;

(a) determining a relationship between the plurality of spectral sensitivity regions and temperature,

(b) determining a correction factor for each of the spectral sensitivity regions based on the relationship determined by step (a) and the current temperature, and

(c) correcting the output of the light receiving element by multiplying the output of each of the spectral sensitivity regions by the corresponding factor determined in step (b).

16. A method for correcting an amplitude of a light receiving element output signal for changes due to temperature, comprising:

determining correction formulas for the light receiving element output signal amplitude changes due to temperature based on at least outputs of a light sensitivity detection device;

determining a current temperature; and

correcting the amplitude of the light receiving element output signal at the current temperature based on at least the outputs of the light sensitivity detection device and the correction formulas, wherein the current temperature is determined by a microprocessor of a light sensitivity correction device based on an output of an optically shielded pixel element.