Self-contained covert image

• US 4,360,548 A
• Filed: 10/24/1980
• Issued: 11/23/1982
• Est. Priority Date: 10/24/1980
• Status: Expired due to Term

• Current Assignee: The Standard Register Company (Middleby Corporation)
• Original Assignee: The Standard Register Company (Middleby Corporation)
• Inventors: Skees, Hugh B., Parenti, Frank V.
• Primary Examiner(s): Morgenstern, Norman
• Assistant Examiner(s): Bell, Janyce A.
• Application Number:
  US06/200,449
• Time in Patent Office: 760 Days
• Field of Search: 427/145, 427/150, 427/151, 427/7, 283/8 B, 283/9 R, 434/328, 428/29, 428/320.8, 428/321.5
• US Class Current: 428/29
• CPC Class Codes: B41M 5/165 characterised by the use of microcapsules; Special solvents for incorporating the ingredients
• CPC Class Codes: B44F 1/10 Changing, amusing, or secret pictures
• CPC Class Codes: Y10S 283/901 Concealed data
• CPC Class Codes: Y10S 283/902 Anti-photocopy
• CPC Class Codes: Y10T 428/249997 Encapsulated liquid

Abstract

A hidden image, which can be made detectable by rubbing, is produced by applying to a substrate surface a first ink-like material in image configuration, then applying a second ink-like material to cover the image and an area surrounding the image. Each of the first and second ink-like materials contain one of a color-forming pair of reactants which are colorless or light colored in their unreacted states, but which together produce a colored product when brought into reactive contact. Separation of the two reactants is assured by encapsulating at least one of the reactant pair. Reactive contact is caused by rubbing the printed area or otherwise applying sufficient pressure to rupture the capsules, releasing one of the reactants into intimate contact with the other reactant.

Claims

1. A material bearing a self-contained covert image, comprising:

a substrate;

a coating of a first ink-like material on said substrate in the configuration of the desired covert image; and

a coating on said substrate of a second ink-like material which is tinted with a color which does not obscure the image obtained after reaction of said first and second ink-like materials, said second ink-like materials being printed in the form of an overt image, said overt image being sufficiently different from said covert image to confuse the eye of the observer and thereby make it more difficult to recognize said covert image;

wherein each of said first and second ink-like materials contain an opposite one of a color-imaging pair of reactants which are colorless or light colored in their unreacted state, but which together produce a colored product when brought into reactive contact, and wherein said overt image coating is at least partially coextensive with said covert image coating and at least one of said first and second ink-like materials are micro-encapsulated to prevent reactive contact of the materials and to permit reactive contact after rupture of the microcapsules.

2. A covert image bearing material in accordance with claim 1, wherein said substrate is paper.

3. A covert image bearing material in accordance with claim 1, wherein said first ink-like material is in a formulation making it printable by a standard printing press.

4. A covert image bearing material in accordance with claim 1, wherein only said second ink-like material is microencapsulated.

5. A covert image-bearing material in accordance with claim 1, wherein said overt image is in the form of a scrambled block-out design or pantograph.

6. A method of producing a covert image, comprising:

printing the configuration of the desired covert image onto a substrate in a first ink-like material; and

printing onto said substrate a second ink-like material which is tinted with a color which does not obscure the image obtained after reaction of said first and second ink-like materials, said second ink-like material being printed in the form of an overt image, said overt image being sufficiently different from said covert image to confuse the eye of the observer and thereby make it more difficult to recognize said covert image;

wherein each of said first and second ink-like materials contain an opposite one of a color-imaging pair of reactants which are colorless or light colored in their unreacted state, but which together produce a colored product when brought into reactive contact, and wherein said overt image is at least partially coextensive with said covert image and at least one of said first and second ink-like materials are micro-encapsulated to prevent reactive contact of the materials and to permit reactive contact after rupture of the microcapsules.

7. A method in accordance with claim 6, wherein said overt image is in the form of a scrambled block-out design or pantograph.

8. A method in accordance with claim 6, wherein said step of printing the configuration of the desired covert image is accomplished first, followed by said step of printing said second ink-like material.