Frequently Asked Questions

Phospho-rescent materials	Quality	The materials become self-luminous to glow in darkness by emitting light energy accumulated in the daytime or under light.
	Feature	Although the emission is not so strong and the visibility decreases with time, such visibility can last for a certain period of time and can work as marks.
Fluores-cent materials	Quality	The materials look vibrantly in the areas under light by reacting to such light.
	Feature	Although there is no visibility in darkness, the materials, whose color is vibrant and outstanding, can be effectively used for display in daytime or under light.
Reflective materials	Quality	The materials can look shining by reflecting the light received when seeing them from the light source in darkness.
	Feature	Light source is required to see them in darkness. However, by receiving light, the materials can be quite noticeable even from afar, and the visibility in environment where light is being used is quite good.

Materials are inorganic and semi-permanent, and are not deteriorated by ultraviolet rays, etc. No big changes were detected under the xenon arc lamp test (an accelerated weathering test) for 2,030 hours (equivalent to 5 years) in our phosphorescent sheet. However, as organic materials are mixed with them upon being produced as products, actual weather resistance will become shorter, so, when the phosphorescent sheet is  installed, the surface and the edge protection is necessary.

* This test result was a measured value and not the guaranteed one.

There are four units (total luminous flux, illuminance, light intensity, and luminosity) to measure brightness. The brightness of phosphorescent products is represented by the “Luminosity”, and the intensity of light that illuminates the products by the “Illuminance”.

• Luminosity:Value that represents “how much a light source looks bright”. Amount of light being emitted from a measuring surface. [milli-candela(mcd/㎡)]
• Illuminance: Brightness of a surface that is illuminated by a light source. Amount of light being irradiated to a measuring surface. [lux(lx)]

Indication on luminosity and human visual recognition

Luminosity (Unit：mcd/㎡)	Human visual recognition in darkness	Recognizable	Unrecognizable
200 or more	The level you can read letters.	-	-
5 or more	You can read letters somehow.	10 people	Nil
3 or less	You can recognize the outline of objects.	10 people	Nil
2 or less	Becoming vague, but you can recognize the objects somehow.	10 people	Nil
1 or less	You can hardly recognize the objects.	3 people	7 people
0.3	The limit that men’s eyes can recognize (*)	-	-

*DIN67510: Deutsche Industrie Normen (Long persistence pigments and product)

Although “brightness” and “darkness” are the matter of sense and there are individual differences, it is thought that, in fact, the illuminance that you can visually confirm in total darkness is about 3mcd/㎡ or more.

Indication of Illuminance by location (Excerpt from JIS Z9110)

Location	Illuminance
Sunny / daytime / sunlight	100,000
Cloudy / daytime / sunlight	32,000
Rainy / daytime / sunlight	15,000
At the time of sunrise and sunset	300
Candle (distance 10cm) *1	200
Candle (distance 30cm) *1	15
Under a streetlight of height 5m (single fluorescent lamp) *2	10
Under moonlight at a full moon	0.24
Under star light without moon *3	0.001
Stadium	3,000
Convenience store	1,500
Studio of television broadcast	1,000
Brightness on a desk when you study	500-750
Office (fluorescent lighting)	400-500
Indoor fire escape, warehouse, living room	30-75
Bedroom	10-30
During break in a cinema theater	10-20
Seats during a movie in a cinema theater	1-2

*1 Diameter 20mm, core diameter 2.2mm, minor axis of flame size 15mm, major axis 30mm
*2 Height of an adult face (8lx at the height of 1m, 5lx at the ground)
*3 Equivalent to the distance of about 3 to 4m from a candle whose diameter and core diameter 　　 are 20mm and 2mm respectively.

The brightness of lx and cd cannot be compared relatively, but, as a matter of calculation, the brightness that is illuminated by the light source of 1,000mcd (1 candela) at a distance of 1m is set to 1 lux (Illuminance = light intensity (cd) / square of the distance). 　

Afterglow luminosity of phosphorescent products becomes longer generally with higher illuminance of excitation and longer irradiation time. There, however, is saturation time correlated to irradiation time by respective illuminance, at which point the luminosity will not become higher any more even if the irradiation time is extended longer. (*)

*The luminosity (initial and afterglow) of phosphorescent products varies depending on the difference of emitting color, particle diameter or paint film thickness of materials, etc

It is important how much the phosphorescent material can absorb the light energy emitted from the light source.
Light energy is determined by wavelength and is classified as shown in figure 1.

Figure 1 - Wavelength classification

It is generally recognized that "phosphorescent materials absorb ultraviolet rays and luminous." because the phosphorescent material absorbs wavelengths of 250 to 480 nm, which occupies most of the wavelength of ultraviolet rays. (See figure 2.)

Figure 2 - Excitation and emission spectra

However, since it also absorbs visible light wavelengths of 380 to 480 nm, white LEDs with sharp peaks in the wavelength range of 460 to 470 nm are also effective.

In the case of outdoors, sunlight is the light source, so the conditions for absorbing light energy are in place. (Sunlight has a wide wavelength range of 300 to 3,000 nm, and the intensity of 400 to 700 nm is particularly strong.)

Our phosphorescent products (*1) are fully compliant with the afterglow luminance specified in ISO 22578 and DIN 67510-4. Measured values according to ISO 22578 and DIN 67510 are shown in Table 1.

Table 1 - Afterglow luminance data

Our products	Luminance(mcd/㎡) after a decay time of
	2	10	20	30	60	120	720
Aluminum phosphorescent sign (*1)	-	-	698	-	231	108	15
phosphorescent sheet (Ultra-high) (*2)	-	-	402	-	117	52	6
phosphorescent sheet (Ultra-high) (*3)	2,960	660	-	210	94	-	-

(*1) Aluminum Phosphorescent Sign, Aluminum Phosphorescent Non-slip, Phosphorescent Road Studs, Phosphorescent Sheet, Reflective Luminous Sheet
(*2) Measurement of afterglow luminescence according to ISO 22578:2021 and JIS Z 9098:2016
(*3) Measurement of afterglow luminescence according to DIN 67510-4:2008-02

Table1 means that the product has an afterglow time of more than 12 hours in the dark. Therefore, it is very effective when used as a landmark in places where there are no lighting fixtures such as streetlights. (Our estimate is that our products can be installed and maintained at less than a quarter of the cost of LED solar lighting lamps.)

The ISO standards are shown in Table 1.

Table 1 - ISO standard

Number	Title	Corresponding JIS
3864 - 1 : 2011	Graphical symbols - Safety colours and safety signs - Part 1: Design principles for safety signs and safety markings	JIS Z 9101
3864 - 2 : 2016	Graphical symbols - Safety colours and safety signs - Part 2: Design principles for product safety labels	JIS S 0101 (part)
3864 - 3 : 2012	Graphical symbols - Safety colours and safety signs - Part 3: Design principles for graphical symbols for use in safety signs	Non
3864 - 4 : 2011	Graphical symbols - Safety colours and safety signs - Part 4: Colorimetric and photometric properties of safety sign materials	JIS Z 9103
7010 : 2012	Graphical symbols - Safety colours and safety signs - Registered safety signs	JIS Z 8210 (part)
16069 : 2004	Graphical symbols - Safety signs - Safety way guidance systems (SWGS)	JIS Z 9095
17398 : 2004	Safety colours and safety signs - Classification, performance and durability of safety signs	JIS Z 9107
22578 : 2021	Graphical symbols - Safety colours and safety signs - Natural disaster safety way guidance system	JIS Z 9098

The JIS are shown in Table 2.

Table 2 - JIS

Number	Title	Remarks
Z 9095 : 2011	Graphical symbols -Safety signs - Safety way guidance systems (SWGS) - Phosphorescence type	It is a standard for evacuation guidance system for phosphorescent safety signs when evacuating from a building to the outdoors.
Z 9096 : 2012	Safety sign and guidance line of phosphorescent type on floor	It is a standard for installing phosphorescent safety signs and guidance lines on the floor.
Z 9097 : 2014	Tsunami evacuation guidance - Safety signing system	It is a standard that safely guides people to evacuation sites when a tsunami occurs.
Z 9098 : 2016	Hazard specific evacuation guidance sign system	It is a standard that guides people to evacuate safely to evacuation sites with signs when a natural disaster occurs.
Z 9107 : 1998	Safety sign board	It is a standard for the performance and test methods of general safety sign boards, fluorescent safety sign boards,and phosphorescent safety sign boards.
Z 9107 : 2008	Safety colors and Safety signs - Classification, Performance and durability of Safety signs	The title of the standard has been adjusted to ISO 17398.

The DIN are shown in Table 3.

Table 3 - DIN

Number	Title
67510 - 1 : 2020	Phosphorescent pigments and products - Measurement and marking at the producer
67510 - 4 : 2008	Phosphorescent pigments and products - Products for phosphorescent escape route systems - Markings and applications

Standards and Regulations we MEET:

JIS Z 9098:2016
Hazard specific evacuation guidance sign system

Japanese Industrial Standards (JIS) are the standards used for industrial activities in Japan. JIS Z9098 stipulates a disaster - type evacuation guidance sign system used when evacuating to a safe place in preparation for disasters such as tsunamis, floods, landslides, and large - scale disasters.
This standard stipulates the lower limit luminance of the phosphorescent material used for disaster type evacuation guidance signs as a measure against darkness at night or when power is lost.

The minimum requirement for the luminance decay properties of phosphorescent materials used in components of the Hazard specific evacuation guidance sign system shall be as given in Table 4 for the category of luminance classification.

Table 4 - Luminance decay classification of outdoor phosphorescent safety signs

classification	Minimum luminance at 720 min decay time mcd/㎡
Ⅰ	3
Ⅱ	10

Luminance test of the phosphorescent disaster type evacuation guidance sign uses a xenon lamp, irradiates with ultraviolet intensity (measurement wavelength range 360 to 400 nm) 400 μW for 60 minutes, blocks the light, and measures the value 720 minutes later.

　

JIS Z 9107:2008
Safety colors and Safety signs - Classification, Performance and durability of Safety signs

This standard is a Japanese Industrial Standard created based on ISO 17398:2004 by changing the technical contents in consideration of the actual situation in Japan. Defined the performance standards related to safety signboards having a phosphorescent performance. Based on the classification method related to various conditions such as the color material of the safety sign, expected usage environment, main structural materials, lighting method, mounting method, gloss, etc., the performance standards and test methods required for each are stipulated.

The minimum phosphorescence luminance shall fall into one of the four Classifications shown in Table 5.

Table 5 - Minimum phosphorescence luminance of phosphorescent material using fluorescent lamp

classification	Minimum luminance(mcd/㎡) after a decay time of
	2 min	10 min	20 min	30 min	60 min
JA	210	50	24	15	7
JB	440	105	50	31	15
JC	880	210	100	62	30
JD	1,760	420	200	124	60

Conditions of excitation luminosity: Irradiate fluorescent lamp 200 lux for 20 minutes.

DIN 67510 Part4:2008
Phosphorescent pigments and products - Products for phosphorescent escape route systems - Markings and applications

The DIN standard is a national standard of the Federal Republic of Germany created by the German standard (Deutsches Institut für Normung). This standard specifies the requirements and test methods for phosphorescent products. The categories of luminance decay classification are shown in the table 6.

It makes specifications for designing phosphorescent products which can be selected and used for specific excitation lighting. In addition to the tests of phosphorescent properties in DIN 67510-1 and DIN 67510-2, it defines mandatory and optional loading tests for durability, along with the associated test conditions. The products defined in this standard are used in escape route systems or in individual applications.
The geometric shapes and the symbols contained in them are specified in standards such as DIN 4844-2, DIN 4844-3 and BGV A 8.
This standard does not apply to products which contain radio additives or phosphorus.

Table 6 - Minimum phosphorescence luminance of phosphorescent material using Xenon lamp

classification	Minimum luminance(mcd/㎡) after a decay time of
	2 min	10 min	30 min	60 min
A	108	23	7	3
B	210	50	15	7
C	690	140	45	20
D	1,100	260	85	35
E	2,200	520	170	70

Conditions of excitation luminosity: Xenon lamp 1,000 lux for 5 minutes.