ISO TS 20328:2016 download free.Imaging materials-Lenticular lens sheet – Measurements and specifications of dimensions.
L.enticular lens are an array of magnifying lenses, which can generate a desired visual perception, including 3D effect, animation and flips, when the underlying interlaced printed image is viewed from different angles. The most widespread use of this technology Is in lenticular printing, for use In packages, display posters, promotional buttons, magnets, coasters, collectibles, signs, menu boards. postcards and business cards,
It is reported that the market size of lenticular sheets is over 100 million m2 and the market is growing. Moreover, the image qualities of lenticular printing have improved dramatically, and further improvement Is expected in the future. While production of Ienticubr sheets with a lens frequency of 100 lines per inch (Ipi) is routine, products with 200 Ipi are also currently available. To produce the optimal perceptive experience, the right choice of lenticular sheet is crucial. Different use cases require different lens frequencies. For a 2D view application, a 200 IpI material can be optimal, and for multiview 3D effect viewed from one meter or further, a 12 ipi material can be optimal. On a separate note, lentlcular sheets with higher lens frequency can be thlnner therefore, Increasing Its potential In high quality packaging and a variety of printings.
The multi-step process of lenticular printing involves creation of a lenticular image from at least two existing images and its combination with a lenticular sheet. The combining process can either be a 1) direct printing of the images on the lenticular sheets or 2) pasting the lenticular sheet and printed images. This process can be used to create various frames of animation (motion perception), offsetting the various layers at different increments (3D perception) or simply to show a set of alternate images which appear to transform into each other.
Major factors Influencing the quality of a lenticular Image is the precision In the dimensions of the lenticules In the lentlcular sheet and the prInted Interlaced Image and the precision In the positioning of the lens array and the Interlaced Images. Poor precision results in poor Image quality and poor precision in the dimensions of lenticules in the lenticular Lens sheet can result In low production yield, consequently resulting in higher costs.
Therefore, the demand for Improving the precision In the dimensions ci the lenticuies in a lenticular lens sheet has been high. The standardization of the measurements of the dimension of the lenricules in a lenticular lens sheet has been requested from the market.
This Technical Specification specifies the measurements and specifications of the dimensions of a lenticular lens sheet. It describes measurement methods and specifies the nominal sizes and target dimensions with tolerance. it also describes methods to test the stability oldimensions of the lenticutar lens sheet.
This Technical Specification Is applicable to lenticular lens sheets used in lenticular prints, including those that give an Image the illusion of depth or make Images appear to change/move as the Image Is viewed from difrerent angles. loth impact and non.lrnpact printing can be used to generate the Images. Examples of the former are off.set, gravure and flexography, while the examples of the latter are silver halide. inkjet, dye diffusion thermal transfer and electrophotography.
2 Normative references
The following documents, in whole or in part, are normatively referenced in ISO TS 20328 and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (Including any amendments) applies.
ISO 11359-2. PlastIcs — Thermomechanical analysis (TMA) — Part 2: DeterminatIon of coefficient of linear thermal expansion and glass transition temperature
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
lenlicular lens
array of magnifying seml•cyllndrlcal lenses, designed to produce a desired percepLlon such as 3D. motion or morphing, to the underlying Interlaced Image
EXAMPLE This technique is widely used in lenticular printing, wherein the lenticular lens is used to provide an Illusion of depth, change or motion to an underlying Interlaced Image when viewed From different angles.
Note Ito entry Schematic dlarams of a lenticular sheet is shown in Flurr 1 (top view) and Eigure_l (side view).
4.2 Width of a lenticule
4.2.1 Measurement equipment
Calibrated dimension measurement equipment shall be used. The spatial resolution capability of the equipment shall be Finer than 20 pm.
For example, a stylus type surface measuring Instrument, used typically for measuring surface roughness and contour, can be used. An example for the stylus is 5 pm diamond stylus tip with 40 angle.
4.22 Measurement procedures
The sample should be equilibrated to the standard ambient conditions for one hour before measurements. The measurements should be made at the standard ambient conditions.
An area that includes 20 or more lenUcules shall be measured. As shown In Figure La valley, represented by 3” Is located between two lentlcules. The width ola lenticule (WI) Is the distance between any two adjacent valleys. The measurement shall be performed both In the forward and backward directions.
The distance from the first valley to the 21st valley, i.e. the combined width of 20 lenticules, shall be measured.
The measured width of each lenticule shall be recorded and be expressed in pm.
423 Reporting of the precision The following shall be reported:
a) the measured average width oIthe lenticule;
Average WI is calculated by dividing the combined length by the number of tenticules. as shown in Formula (1). The width shall be expressed in pm;
4.4 Temperature and humidity dependence
4.4.1 General
When Interlaced Images are directly printed on lenticular lens sheets or the printed interlaced Images are attached to the lenticular lens sheets, the amb.ent temperature and/or humidity of the work area may not be controlled. Nevertheless, stability of the dimensions of the ienticubr lens sheet is a critical factor for ensuring coordination between the array of lenses and the printed interlaced images.
In this subclause, procedures for measuring the temperature and humidity dependence of the dimensions of lenticular lens sheet are described.
4.4.2 Measurement equipment and procedures
The length of a strip of the lenticuiar lens sheet shall be measured under different temperature and humidity conditions.
The precision otthe measurements of the dimensions shall be smaller than 0.01 % In terms of the ratio of change (In dimenslon).to.orlglnal length.
An example of the measurement procedure is as follows.
Size of the strips: Width = 4 mm and length = 20 mm; here the length, representing the distance along X-axis In Figure 1.. Is the distance between the two clipped edges of the lentlcular lens sheet.
Equipment: An example of the equipment used to measure the dimensions of the sheets Is shown in
The terminal c pull the sample strip with 10 mN tension.