What is FLASH PRINT?
This is a magic trick printing technology that retroreflects incident light to reveal different designs. When a flash is used to take a picture with a smartphone or digital camera, the light is reflected and the hidden design or text is made to emit light and recorded by the camera.
*The same effect can be achieved with headlights
①About Triggers
The trigger for the flash print to make the hidden design appear is "retroreflective light in the line of sight". The hidden design can be seen by taking a flash photo or by matching the light of the light to the line of sight.
②Technical Overview | Product Specifications
Retroreflection is a method of reflection in which, unlike ordinary reflection, light is reflected directly back toward the light source regardless of the direction from which it strikes.FLASH PRINT uses retroreflective material, a patented printing technology that allows SO-KEN to switch between two different designs through a printing data processing method of its own invention.
| Retroreflective *FLASH PRINT fall under this category. | Diffuse reflection |
| The light that hits it is reflected straight back toward the light source, so it appears bright and shiny when viewed from the driver. | General light reflection. Light that hits the surface is diffused in different directions due to surface irregularities. |
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| Retroreflective *FLASH PRINT fall under this category | Diffuse reflection | Specular reflection |
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| If there is reflective material on the surface | Rough surfaces such as concrete and cloth, etc. | Mirrors, metal surfaces, etc. |
About an arithmetic data processing method that does not require addition.
This is a special placement printing technology completed only by inkjet that allows two different designs to be seen on one medium: a normal design with non-translucent ink printed on a retroreflective sheet and a design with translucent ink that retroreflects when illuminated by light.
How the hidden design is visible
The hidden design is reproduced by retroreflected "light" such as when taking flash pictures. Since black light does not exist, areas that do not glow are recognized as black.
Ink specifications and weather resistance
MIMAKI - Genuine eco-solvent ink CMYKW
| Weather resistance |
| Because of exposure to the outdoors, multiple conditions such as light, rain, wind, and the compatibility between the material and our inks It varies greatly. SS21/ES3/Eco-HS1/HS inks are irradiated with a xenon arc weatherometer at 180W/m² for 1560 hours. In the case of SS21/ES3/Eco-HS1/HS inks, we have confirmed that no significant fading occurs when the inks are irradiated with a xenon arc weatherometer for 1560 hours at 180W/m² and sprayed for 18 minutes during 120 minutes of irradiation. |
| Flash Print Product Specifications | |
| Ink | Oil-based ink for outdoor use. |
| Paper | Outdoor paper. |
③Notes on installation and use
| Durability period of FLASH PRINT |
| Approximately 3 years for outdoor use. |
Brightness of the environment suitable for gimmicks
It is difficult to see the hidden design in environments with illumination of more than 1600 lux, both indoors and outdoors.
| Reference | |||
| outdoor | Illuminance by natural light | in clear weather | Approx. 100,000 lux |
| cloudy weather | Approx. 30,000 to 70,000 lux | ||
| in case of rain | Approx. 10,000 to 30,000 lux | ||
| Sunset on a clear day | Approx. 100 to 500 lux | ||
| Night of the Full Moon | 0.2 lux | ||
| indoor | Illuminance by artificial light | Department | Approx. 500 to 1,000 lux |
| Museum | Approx. 50 to 500 lux | ||
Differences in the visibility of hidden designs depending on the brightness of the environment
Results will vary depending on the brightness of the environment even at the same output. The gimmick cannot be reproduced outdoors in daylight or in an environment that is too bright.
| Design data |  |
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| Normal visible design | Hidden design | ||
| Light source for visibility | Indoor light or natural light | Reflected light during flash photography, etc. | |
| Feature | Recognizes "reproduction by color" by the brightness of ambient light. | Recognize "light reproduction" of retroreflections. | |
| Visibility | Bright space | As with colors seen in daylight, visibility increases when the surroundings are bright. | As in daylight, light is not visible when the surroundings are bright. |
| Dark space | As with colors seen at night, visibility is reduced when the surroundings are dark. | Similar to light seen at night, visibility increases when the surroundings are dark. | |
| When shooting with flash | Bright color | Less susceptible to backlighting effects when shooting with flash (Affects visibility of hidden design) | Light is bright and highly visible |
| Dark color | Backlighting effect when shooting with flash makes it invisible. | Dark light and low visibility | |
| Visibility during flash photography based on a combination of the above data | ||
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| In a dark space (approximate example: under a streetlight at night) | In a standard space (standard example: in a department store retail store) | In brightly lit spaces (standard example: inside a pachinko parlor) |
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| This is a case where reproduction by light is superior to reproduction by color. | This is a case where reproduction by color is superior to reproduction by light. | |
Retroreflecting to the angle of incidence
Retroreflects in the same direction as the angle of incidence of light. It is not visible when the light is not irradiated or from an angle different from that of the irradiated light.
Cautions for the environment
In a typical bright environment, there is always an irradiated light. If your eyes are on the same line as the irradiated light, you will see the hidden reflected light. This is an unavoidable phenomenon due to technical characteristics.
Construction Precautions
The following pages provide detailed information on construction precautions and differences in the way flash photography looks depending on the model of the smartphone.