EP0711995A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Linear integrating cavity light source for infra-red illumination of sensitized media
Assignee: Eastman Kodak Co
•
Filing: 1995-10-25
•
Granted: —
•
Expires: 2015-10-25
Abstract
Abstract A highly uniform infrared illumination source for illuminating a stripe of a moving sensitized web (14) for line scan imaging of imperfections in the coating on the web by a CCD imaging camera (18). A light integrator (30) having an elongated housing formed with side (32) and end walls (34,36) defines a linear light integrating cavity (38) having diffusely reflecting interior wall surfaces. An elongated array (60) of infrared LEDs is spaced along the side wall for emitting light into the cavity (38) for integration within the cavity (38). A longitudinally extending slit (44) is formed in the side wall (32) through which a diffuse, linear light beam exits the elongated slit (44) having a varying longitudinal intensity profile. The intensity of the light emitted by the LEDs (70₁-70 n ) is modulated in an intensity pattern that alters the varying longitudinal intensity profile of the linear light beam to provide a desired longitudinal intensity profile of the stripe of diffuse illumination. Preferably, the intensity modulation renders more uniform the longitudinal intensity profile of the linear light beam illuminating the web as viewed by the imaging camera (18). The desired light intensity profile along the length of the emitted light beam is achieved by clustering the LEDs (70₁-70 n ) with LED drive circuits (80₁-80₅) operated at different drive currents as a function of a set point control signal appropriate to the characteristics of the imaging camera (18) and a transmitted light intensity feedback signal to maintain the intensity pattern of the LEDs and the uniform intensity profile as viewed by the imaging camera (18) regardless of the optical density of the web (14).
Inventors
- 👤 H. Galen c/o Eastman Kodak Co. Parker
- 👤 Robert B. c/o Eastman Kodak Co. Bilhorn
- 👤 Martin C. c/o Eastman Kodak Co. Kaplan
- 👤 Russell J. c/o Eastman Kodak Co. Palum
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 10:35
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/89; G01N21/8914; G01N21/8916; B; B65; B65H; B65H26/00; B65H26/02; G01N21/8901; B65H2301/00; B65H2301/50; B65H2301/54; B65H2301/542; B65H2515/00; B65H2515/84; B65H2553/00; B65H2553/40; B65H2553/42; B65H2701/00; B65H2701/10; B65H2701/17; B65H2701/175; B65H2701/1752; G01N2021/8908
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
177 words
A linear light integrator (30) for use in illuminating a web (14) with an elongated stripe of diffuse illumination comprising: an elongated housing formed with side (32) and end walls (34,36) defining a light integrating cavity (38) having diffusely reflecting interior wall surfaces, the housing side wall (32) having a longitudinally extending slit (44) through which diffuse light exits the cavity (38); an elongated array (60) comprising a plurality of discrete light sources (70₁-70 n ) supported with respect to the elongated housing to emit light into the cavity (38), so that the emitted light is integrated within the cavity by reflection from the interior wall surfaces thereof and the integrated light forms a linear light beam exiting the elongated slit (44) having a varying longitudinal intensity profile; and means (16) for modulating the intensity of the light emitted by the discrete light sources (70₁-70 n ) in a predetermined intensity pattern for altering the varying longitudinal intensity profile of the linear light beam to provide a desired longitudinal intensity profile of the stripe of diffuse illumination.
Claim 2
Dependent Claim
122 words
The linear light integrator (30) of Claim 1 wherein the intensity modulating means further comprises: means (40) for providing a set point control signal defining an illumination intensity level of the stripe of illumination; means for connecting the plurality of light sources (70₁-70 n ) into a further plurality of groups in a predetermined relationship; and a plurality of drive circuits (80₁-80₅) for driving each of the plurality of groups of light sources (70₁-70 n ) at a plurality of light intensities corresponding to the predetermined intensity pattern as a function of the set point control signal for altering the varying longitudinal intensity profile of the linear light beam to provide a desired longitudinal intensity profile of the stripe of diffuse illumination.
Claim 3
Dependent Claim
141 words
The linear light integrator (30) of Claim 2 further comprising: means for monitoring (20) the intensity of the linear light beam modulated by the web (14) and providing an intensity feedback signal varying as a function of the light transmissive characteristics of the web (14); means for comparing the set point control signal with the intensity feedback signal and deriving an error signal from the comparison; and wherein the plurality of drive circuits (80₁-80₅) further comprises: means (84) for providing drive energy to the plurality of light sources (70₁-70 n ) in each group to establish the plurality of light intensities of the groups of light sources; and means responsive to the error signal for adjusting the drive energy provided to maintain the plurality of light intensities in a constant relationship regardless of the light transmissive characteristic of the web (14).
Claim 4
Dependent Claim
39 words
The linear light integrator (30) of Claim 3 wherein the plurality of light sources (70₁-70 n ) is supported in an equally spaced linear light source array (60) aligned in parallel with the longitudinally extending light exiting slit (44).
Claim 5
Dependent Claim
84 words
The linear light integrator (30) of Claim 4 wherein: the plurality of light sources (70₁-70 n ) are equidistantly spaced in the light source array (60) in relation to an array center point (46) of the light source array (60) aligned with a slit center point (46) of the longitudinally extending light exiting slit (44); and the connecting means makes electrical connections of groups of the light sources selected from the light source array (46) on either side of the array center point (46).
Claim 6
Dependent Claim
251 words
A scanner (10) for scanning an illuminated stripe of a moving web (14) for detecting defects in the web comprising: a linear light integrator (30) for use in illuminating the web (14) with a stripe of diffuse illumination at a web scanning plane further comprising: an elongated housing formed with side (32) and end walls (34,36) defining a light integrating cavity (38) having diffusely reflecting interior wall surfaces, the housing side wall (32) having a longitudinally extending slit (44) through which diffuse light exits the cavity; and an elongated array (60) of a plurality of discrete fight sources (70₁-70 n ) supported with respect to the elongated housing for each emitting fight into the cavity (38), so that the emitted light is integrated within the cavity (38) by reflection from the interior wall surfaces thereof and the integrated light forms a linear light beam exiting the elongated slit (44) having a varying longitudinal intensity profile; a line imaging camera (18) imaged on a image scan line of the illuminated stripe of the web (14) for developing an output image signal varying in magnitude as a function of the transmission of light through areas of the web (14) that exhibit normal and defective densities; and means for modulating (16) the intensity of the light emitted by the discrete light sources (70₁-70 n ) in an intensity pattern to provide a desired longitudinal intensity profile of the stripe of diffuse illumination illuminating the web (14) as viewed by the line imaging camera (18).
Claim 7
Dependent Claim
123 words
The scanner (10) of Claim 6 wherein the intensity modulating means further comprises: means (40) for providing a set point control signal defining an illumination intensity level of the stripe of illumination for the imaging camera (18) being used; means for connecting the plurality of light sources (70₁-70 n ) into a further plurality of groups in a predetermined relationship; a plurality of drive circuits (80₁-80₅) for drag each of the plurality of groups of light sources at a plurality of light intensities corresponding to the predetermined intensity pattern as a function of the set point control signal for altering the varying longitudinal intensity profile of the linear light beam to provide a desired longitudinal intensity profile of the stripe of diffuse illumination.
Claim 8
Dependent Claim
139 words
The scanner (10) of Claim 7 further comprising: means for monitoring the intensity of the linear light beam modulated by the web (14) and providing an intensity feedback signal varying as a function of the light transmissive characteristics of the web (14); means for comparing the set point control signal with the intensity feedback signal and deriving an error signal from the comparison; and wherein the plurality of drive circuits (80₁-80₅) further comprises: means (84) for providing drive energy to the plurality of light sources (70₁-70 n ) in each group to establish the plurality of light intensities of each group of light sources; and means responsive to the error signal for adjusting the drive energy provided to maintain the plurality of light intensities in a relative intensity pattern relationship regardless of the light transmissive characteristic of the web.
Claim 9
Dependent Claim
126 words
The scanner (10) of Claim 8 further comprising: means for monitoring the intensity of the linear light beam modulated by the web (14) and providing an intensity feedback signal representative thereof to each of the plurality of drive circuits (80₁-80₅), the intensity feedback signal varying as a function of a characteristic of the web (14); and wherein the plurality of drive circuits (80₁-80₅) further comprise: means (84) for providing drive energy to the plurality of light sources(70₁-70 n ) in each group to establish the plurality of light intensities of the groups of light sources (70₁-70 n ); and means (84) responsive to the intensity feedback signal for adjusting the drive energy provided to maintain the plurality of light intensities in the relative intensity pattern relationship.
Claim 10
Dependent Claim
118 words
The scanner (10) of Claim 6 wherein: the plurality of light sources (70₁-70 n ) is supported in an equally spaced linear light source array (60) aligned in parallel with the longitudinally extending light exiting slit (44) to emit light into the cavity (38) from the cavity side wall (32) at an angular displacement of greater than 0° and less than 90° with respect to the elongated slit (44), so that the light emitted into the cavity (38) is not directed directly into the slit (44) or against the side wall interior surface directly opposite to the slit (44) and the reflection is not directly visible through the light exiting slit (44) from the line imaging camera (18).
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.