How are those cool anime 3D Flip Poster you see in toy stores made?

I have been very interested in this kind of cool 3d Depth Lenticular painting since I was a child. Among the toys that are commonly seen in toy stores, there are always those sold, there are all kinds of surprising posters; there are also those that change actions when they turn around, and the tiger goes from "lurking claws and enduring" to baring its teeth and claws in an instant... Whenever I pass by a toy store, I can't help but stop and check if there are any new products...

So how are these Anime-Flip-Picture Poster made?

Principle of 3D Depth Stereoscopic

Let's talk about the structure first: the surface of this 3D Lenticular card is actually covered with a layer of cylindrical Lenticular lenses, that is, when we touch the surface with our hands, there are many regular concave and convex lines (we call it Lenticular lenses). When this layer of Lenticular lenses covers the plane painting, the picture has a 3D depth effect. Let's look at what stereo is. Pay attention to the plane painting under each small Lenticular lens in the picture below: it is composed of slices of the left (light gray block) image and the right (dark gray block) image.
The principle is to use the refraction of light by the lens. Our left eye can see the left image, and the right eye can see the right image. This produces a parallax, and the stereo effect of the 3D Lenticular card comes out~

Multi-image principle

When we want to produce a bouncing and flipping image effect, that is, the multi-image effect of "turning to change the image", we have to control the refraction and focus of light. For example, when we look directly at it, we can only see the dark sliced painting in the picture below. If we turn the card to change the angle, we can only see the light sliced painting, but not the dark sliced painting.

Let's sort out the logic: First, our viewpoint of the picture moves, and we see different pictures under the lens, and then the content of the picture changes - the picture effect! The structure of this Lenticular card has been fixed since it was produced.
After understanding the structure and principle, we will enter the manufacturing stage~

Lenticular card raw materials

The raw materials of Lenticular cards are very simple, that is, plastic pellets. The key point of manufacturing lies in how to make the structure... We call it lenticular lens

Mold pressing

First, melt the plastic pellets into a semi-liquid state, and then put them into the mold. In this fine mold, one side of the plastic sheet is squeezed into a cylindrical line, while the other side remains flat.

The Lenticular on this cylindrical surface is roughly as shown below...

Cutting into sheets

Then stretch the rolled grating sheet and flatten it to measure the thickness of each part of the grating. This step is very important, because the light needs to be refracted to enter the changing pattern later. If the thickness of each part is inconsistent, the refraction angle will not match everywhere.
After confirmation, the formed Lenticular sheet can be cut into individual sheets for later use.

Testing the Lenticular Lens Sheet LPI

Now we need to align the manufactured Lenticular Sheet to confirm the size of the grating plate and how to align and focus. I couldn't help but recall the card games I played when I was a kid, using puzzle cards to move around on paper to find the answer...

After alignment, it is necessary to sample and test the lens thickness of the single Lenticular card to avoid focusing problems. The fine machine shown in the figure below is required. Previously, only the thickness of the newly manufactured plastic Sheet was measured, and it was impossible to see the fine size of each column like now.

After this, some toughness tests and fracture tests are needed to confirm the stable product life.

Graphic Design

In the principle part, we explained that a plane can achieve a 3D Depth or animated effect because this picture is not an ordinary picture, but a picture made up of several pictures cut into very small linear columns (Lenticular Lens), which are then combined in sequence and interlaced and synthesized by "professional 3D design software". .
Although two pictures are usually enough to create a 3D effect, computers are now very fast at making graphics, so in order to achieve better results, a series of consecutive pictures are often used to combine and display.
When synthesized in this way, depending on the angle of observation, as long as several pictures in this sequence are seen at the same time, the 3D effect can be felt. For example, the following uses about ten pictures. If you look at them from different angles, you can also see the effect of animation.

If we zoom in on the finished picture, we will find that the blurred part of the picture is composed of many different pictures. This part will be focused on different viewpoints through the refraction of the lens, which will produce a dynamic effect~

Mounting process

After printing, it still looks ordinary, even a low-definition 2D picture...

But put the Lenticular Sheet on it, and you will find that everything has changed! It instantly becomes the most dazzling and dynamic 3D animation! Move the Lenticular sheet, Santa Claus's airplane propeller keeps turning, and the gifts begin to fall slowly.

Mounting finished products

After the plastic layer and the picture layer are made in batches, the finished products will be mounted! After all, the Lenticular Lens Sheet must be mounted with the processed plane to achieve a perfect viewing effect...

Direct printing process

First, the Lenticular sheet is printed on the machine. The picture is printed on the smooth layer. If it is printed on the lens surface, there will be no effect. After printing the smooth layer, white ink or mounting paper is printed to form a dynamic Lenticular painting.

Finally, cut the 3D Lenticular Poster into individual pieces for packaging, and it's done! Back to the three cool display screens at the beginning, we can also know that there are more than three cuts. They are just three main screens, and there are many process frames interspersed in them.