Illumination and detection system for microfiche identification marks
AssigneeCutler-Hammer, Inc.
InventorRomuald Anthony
Life of this patent
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Abstract
In order to detect the identification marks on an exposed transparent card in a stack of similar cards, the identification marks on the exposed card are illuminated by polarized light that is incident at an angle greater than the polarizing angle of the transparent material of the cards. The high angle of incidence and the polarization of the incident light reduce the transmission of light through the exposed card, and thereby reduce the illumination and probability of detection of identification marks on a card adjacent the exposed card.
Claims14
Apparatus for producing a representation of identification marks in an identification area on an exposed card in a stack of transparent cards, comprising:
- a. a light source,
- b. light polarizing means,
- c. means for directing the light from the source to the identification area to impinge on the exposed card at an angle of incidence greater than the polarizing angle of the cards, said means including reflecting means positioned adjacent said transparent cards opposite the identification area to receive the light from the light source and direct it to impinge on the identification area at an angle of incidence greater than the polarizing angle of the cards and said means further including light shielding means to generally confine the light incident on the card to the identification area and means to detect said light.
A method of producing a representation of a pattern of identification marks contained in an identification area on an exposed card in a stack of transparent cards, comprising the steps of:
- a. providing a source of light,
- b. directing the light from the source at the identification area to impinge on the exposed card at an angle of incidence greater than the polarizing angle of the cards,
- c. providing a light detection means,
- d. positioning the light detection means to receive the light reflected from the said marks,
- e. providing light shielding means with an aperture to pass a portion of the light incident on the shield,
- f. positioning said shielding means in the path of light to generally confine the light incident on the card to the identification area,
- g. providing focusing means,
- h. positioning said focusing means in the light path between the shield and the identification area to evenly distribute the light over the identification area,
- i. providing polarizing means,
- j. positioning said polarizer in the light path to polarize the light perpendicular to the plane of incidence,
- k. providing reflecting means, and
- l. positioning said reflecting means to receive the light from the light source and direct it to impinge on the identification area at an angle of incidence greater than the polarizing angle of the cards.
Dependencies are inferred from the claim text.