Moire magnification device

A technology of ripple amplification and safety devices, applied in printing, optics, instruments, etc., can solve the technical difficulties of discrete micro-image arrays, etc.

Inactive Publication Date: 2012-12-26
DE LA RUE INT LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This is due to the enormous technical difficulty in printing two arrays of discrete microimages that are interleaved or registered in a predetermined manner

Method used

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Examples

Experimental program
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Effect test

Embodiment

[0084] Assuming Figure 2 and Figure 5 The structure consists of a microlens 22 with a focal length f of 40 μm or 0.04 mm. In addition, it is assumed that both the microlens and the support substrate 20 are composed of a material having a refractive index n of 1.5. Thus, it follows that the bottom diameter D of the lens is defined by the following expression: D≤f*2(n-1), therefore D≤0.04*2(1.5-1), resulting in D≤0.04mm.

[0085] A value of 0.035mm can then be chosen for D, and a value of 0.04mm (along each axis) for lens spacing B (along each axis), so that the lens array has an f / # number close to 1, with reasonable close packing (lens The gap is 5 μm).

[0086] In the first embodiment, it is assumed that the first image array 10 is required to be located at 2 mm behind the surface plane of the substrate, and the second image array 11 is located at 6 mm behind the surface plane, (note that by definition, the surface plane behind images are virtual, and a more detailed anal...

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Abstract

A moire magnification device is disclosed, comprising a transparent substrate carrying: a regular array of micro-focusing elements on a first surface, the focusing elements defining a focal plane; and a corresponding first array of microimage elements located in a plane substantially coincident with the focal plane of the focusing elements. The pitches of the micro-focusing elements and the array of microimage elements and their relative locations are such that the array of micro-focusing elements cooperates with the array of microimage elements to generate magnified version of the microimage elements due to the moire effect. Along at least one axis across at least a first region of the device, the pitch between the microimage elements and / or between the micro-focusing elements continuously varies across the respective array(s), whereby the moire effect causes different degrees of magnification of the image elements to occur, such that the viewer perceives that the magnified elements are located on a first image surface which is tilted or curved relative to the surface of the device.

Description

technical field [0001] The present invention relates to moirémagnification devices, such as security devices, for example for use on security documents and other items of value, such as banknotes, cheques, passports, identity cards, certificates of authenticity, revenue stamps and others for insuring value or proving personal identity document. The invention also relates to optical devices used in packages and the like. Background technique [0002] For several years, ripple amplification has been used as the basis for safety devices. Several examples are described in WO-A-94 / 27254 and EP-A-1695121. In such devices, a regular array of microfocusing elements defining a focal plane is disposed above a corresponding array of image elements located in substantially alignment with the focal plane of the focusing elements. in plane. The pitch or periodicity of the array of picture elements is chosen to differ from the pitch or period of the focusing elements by a small factor,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B42D15/00G02B27/60
CPCG02B3/0056G07D7/0006G07D7/2066B42D2035/44B42D25/342B42D2035/20B42D15/002B42D25/324B42D25/351G07D7/003G07D7/207
Inventor B·W·霍姆斯
Owner DE LA RUE INT LTD
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