US3536927A - Light and photocell unit for sorting apparatus - Google Patents

Description

azuwvmu 5N Get. 27, 1970 w, 3,536,927

LIGHT AND PHOTOCELL UNIT FOR SORTING APPARATUS Filed Oct. 17, 1968 INVENTOR. WILLIAM H MINK BY GRAY, MASE aoumsom 1 ATTORNEYS BYM Z 49m 3,536,927 LIGHT AND PHOTOCELL UNIT FOR SORTING APPARATUS Wiiliam H. Mink, Columbus, Ohio, assignor to Scientific Advances, Inc, Columbus, Ohio, a corporation of Ohio Filed Oct. 17, 1968, Ser. No. 768,488 Int. Cl. B07c 5/342; G06k 9/06; H01j 39/08 US. Cl. 250-220 13 Claims ABSTRACT OF THE DISCLOSURE Light introduced at the center of a block of transparent acrylic resin spreads throughout and is reflected back from its smooth or coated external surfaces. A transparent opening at each desired area of illumination transmits lightto a test surface from which some of the light is reflected through a filter and to a photocell, both mounted in the opening.

BACKGROUND OF THE INVENTION This invention comprises apparatus for providing light of constantly proportional intensities in a plurality of light reception areas on a test surface and for detecting light reflected from those areas.

Such apparatus is useful for discriminating between desired and undesired documents, such as currency, as in the method and apparatus of United States Patent 3,220,- 549 0f Lan I. Wong. Wongs apparatus includes light source means emitting visible light in a plurality of color sections including respective color components existing on one surface of a desired document. The document to be inspected is held in stationary relationship with respect to the light source, with the surface of interest exposed to the source so as to receive the light therefrom. A plurality of light sensitive means are provided which respectively develop electrical signals having amplitudes responsive to the spectral content of the light received thereby. The light sensitive means are disposed respectively to receive light reflected from a plurality of preselected discrete areas of the one surface of the document, thereby respectively to develop signals in response to the spectral characteristics of the areas. The signals are analyzed, and an indicating signal is provided when the spectral content of the light reflected from each of the areas of the document being inspected conforms to that of a desired document.

Wong uses a fluorescent light to illuminate selected areas of a document through apertures in an opaque plate between the fluorescent light and the document. Light reflected from the various areas is detected by phototubes and photocells mounted in separate compartments having opaque partitions between them and the fluorescent light.

The present invention provides improved equivalent apparatus, all in one compact solid integral unit.

SUMMARY OF THE INVENTION Typical apparatus according to this invention for providing light of constantly proportional intensities in a plurality of light reception areas on a test surface and for detecting light reflected from those areas comprises in combination: a solid internally transparent light distributor member having a face portion adjacent the test United States Patent 0 surface and comprising an illumination area in substantial registry with each light reception area, a recess in the light distributor member having a source of light fixedly mounted therein, and an opening in the light distributor member at each illumination area having a light detector positioned therein to receive light reflected from the test surface.

The external surface of the light detector member typically is substantially smooth over most of its area to contain the light from the source substantially Within the member except at the illumination areas, and at least any region of abrupt change in the external surface may be coated with light reflective material to reduce the loss of light. The member may be made of any suitable material, such as an acrylic resin or other transparent plastic. \Vhere desired, the material may be such that it transmits light over a range of frequencies substantially narrower than the entire visible spectrum. The filtering action can be an inherent property of the material in its usual or natural form; or the material maybe treated, as by tinting, to modify its light transmission characteristics.

The recess and light source typically are substantially centrally located among the light reception areas. Each opening typically comprises a cylindrical portion for holding the light detector (typically a photocell) therein and an outwardly extending conical transparent portion for transmitting light to the illumination area. A light filter may be provided in the opening between the test surface and the light detector, which preferably is isolated from all light except that reflected from the adjacent light reception area on the test surface.

The light distributor member may be made transparent over a narrow region within the periphery of the test surface, and means may be provided for detecting any light passing through the test surface adjacent the narrow region. Suitable detecting means may comprise a solid transparent light reception member (similar to the light distributor member) having a face portion, adjacent the test surface on the side opposite the light distributor memher, that is transparent over a narrow region in substantial registry with the narrow transparent region of the light distributor member, and a light detector therein substantially centrally positioned with relation to the narrow transparent regions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a typical embodiment of the present invention.

FIG. 2 is a front view, with portions cut away, of the apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT document 14 such as a dollar bill or other currency.

Fixedly mounted in a substantially hemispherical recess \l in the light distributor member 11 is a source of light 16 such as an incandescent electric light bulb.

Adjacent each light reception area, such as 17, on the upper surface 13 of the document 14, is an opening 18 in the light distributor member 11. Each opening 18 comprises a cylindrical portion 19 and an outwardly extending conical transparent portion 20 for transmitting light over an illumination area 21 in substantial registry with the light reception area 17. Mounted in the cylindrical portion 19 of the opening 18 are a light detector 22, such as a photocell, and a light filter 23.

The light distributor member 11 may be made of any suitable transparent material such as an acrylic resin or plastic. The external surface of the light distributor member 11 should be substantially smooth over most of its area, to contain the light from the source 16 substantially within the member 11 except at the illumination areas 21. A smooth surface will reflect most of the light impinging upon it at acute angles, but if it is desired to contain a still larger percentage of the light Within the member 11 the external surface can be coated with a suitable light reflective material such as aluminum, silver, or beral. Any discontinuities or abrupt changes in the external surface should be coated with light reflective material.

The surface of the cylindrical portion 19 of each opening 18 may be coated with light reflective material to assure that the light detector 22 is isolated from all light except that reflected from the adjacent light reception area 17 on the test surface 13. The surface of the conical portion 20, however, is left uncoated so that it will be transparent and transmit most of the light to the illumination area 21 and the adjacent light reception area 17.

Thus the-light from the light source 16 mounted in the recess 15 (which preferably, but not necessarily, is substantially centrally located, as shown, among the light reception areas) is transmitted through the light block 11 and the transparent conical portion 20 of each opening 18, to the adjacent illumination area 21 and light reception area 17. A proportion of the light impinging on the light reception area 17, depending upon the characteristics of the document in that area, is reflected to the light filter 23, which permits a fraction of the reflected light within a preselected frequency range to impinge on the light detector 22. The light filter 23 may be omitted in some or all of the openings 18, where the light detector 23 itself has the desired narrow band selectivity or where it is desired to detect light over a broad spectrum. Where it may be desired to filter out certain portions of the spectrum at all areas, the light distributor member 11 may be tinted accordingly. As used in this description and in the claims, transparent means having the property of transmitting light over a useful portion of the visible radiation spectrum, but not necessarily over the entire visible frequency range.

The electrical signals of the light detectors 22 can be measured, if desired, to analyze the light reflecting characteristics of the document 14. Or they can be used to provide the input to suitable control circuits responsive thereto, as in the apparatus of the Wong patent. Any variation in the intensity of the light provided by the light source 16 affects all of the light detectors 22 proportionally, and thus does not diminish the accuracy of properly designed measuring or control circuits.

Where it is desired to test automatically whether the document 14 is complete and properly located, the lower surface 12 of the light distributor member 11 may be made to be transparent over a narrow region within the periphery of the test surface 13, as by providing a transparent groove 26 just inside the periphery, and also providing means for detecting any light passing through the test surface in the narrow region of the groove 26.

Suitable means for detecting any light leaking through the test surface may include a light reception member 30, comprising a substantially rectangular internally trans parent plate similar to the member 11, with a narrow transparent groove 31, in substantial registry with the groove 26, just inside the periphery of the upper face 32 of the member 30. A light detector 33, such as a photocell, may be mounted as shown in a cylindrical opening approximately in the center of the lower surface 34 of the light reception member 30. The external surface of the light reception member 30 preferably is coated with reflective material to contain substantially all light received through the transparent groove 31, and to keep out other light. The surfaces of the cylindrical opening holding the light detector 32 should be transparent, at least adjacent to the light sensitive area thereof, to transmit the light to the detector 33.

While the form of the invention herein disclosed constitutes a preferred embodiment, many others are possible. It is not intended herein to mention all of the possible equivalent forms or ramifications of the invention. It is to be understood that the terms used herein are merely descriptive rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.

I claim:

1. Apparatus for providing light of constantly proportional intensities in a plurality of light reception areas on a test surface and for detecting light reflected from said areas comprising in combination:

a solid internally transparent light distributor member having a face portion adjacent said test surface and comprising an illumination area in substantial registry with each said light reception area,

a recess in said light distributor member having a source of light fixedly mounted therein, and

an opening in said light distributor member at each said illumination area having a light detector positioned therein to receive light reflected from said test surface.

2. Apparatus as in claim 1, wherein the external surface of said light detector member is substantially smooth over most of its area to contain the light from said source substantially within said member except at said illumination areas.

3. Apparatus as in claim 2, wherein at least any region of abrupt change in said external surface is coated with light reflective material. 7

4. Apparatus as in claim 1, wherein said recess and light source are substantially centrally located among said light reception areas.

5. Apparatus as in claim 1, wherein said light detector member is made of an acrylic resin.

6. Apparatus as in claim 1, wherein each said opening comprises a cylindrical portion for holding said light detector therein and an outwardly extending conical transparent portion for transmitting light to said illumination area.

7. Apparatus as in claim 1, wherein each said light dtector is isolated from all light except that reflected from the adjacent light reception area on said test surface.

8. Apparatus as in claim 1, wherein each said light detector comprises a photocell.

9. Apparatus as in claim 1, wherein a light filter is provided in at least one said opening between said test surface and the light detector in said opening.

10. Apparatus as in claim 1, wherein said light distributor member transmits light over a range of frequencies substantially narrower than the entire visible spectrum.

11. Apparatus as in claim 10, wherein said light distributor member is tinted.

12. Apparatus as in claim 1, wherein said light distributor member is transparent over a narrow region within the periphery of said test surface, and wherein means are provided for detecting any light passing through said References Cited test surface adjacent said narrow region. i UNITED STATES PATENTS 13. Apparatus as 1n claim 12, Wherem said detecting A s a means comprises a solid internally transparent light re- 3'1221227 2/1964 Bookout at 209*1116 X ception member having a face portion adjacent said test 3220549 11/1965 Wong 2O9 111'6 5 3,480,785 11/1969 Aufderherde 209111.6 X

surface on the side opposite said light distributor member, said face portion being transparent over a narrow region JAMES W, LAWRENCE, Primary Examiner in substantial registry with said narrow transparent region of said light distributor member, and a light detector CAMPBELL Asslstam Exammer therein substantially centrally positioned with relation to 10 U8. Cl. X.R. said narrow transparent regions. 209

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