A-202

Standard Photoelectric Sensors

Technical Guide

Glossiness

When light is applied to the sensing object, the reflected light

is generally a mixture of regular reflection components and

diffuse reflection components. Glossiness is directly propor-

tional to the light intensity of the regular reflection compo-

nents. In JIS, the glossiness of a glass plate surface having

1.567 reflectivity is defined 100 as the basis of glossiness.

Glossiness of Typical Object Sensed by E3X-NL11 + E32-

S15

Sensing of Transparent Objects with Rotating Fiber Unit

Mounting Bracket

There are transparent films and transparent plastic objects

that change the direction of polarized light when it passes

through the transparent films and transparent plastic objects.

When E3X-NL senses these transparent films and transpar-

ent plastic objects on glossy background objects, such as

glossy paper or metals, E3X-NL will not sense these objects

smoothly in case of an incorrect angle of the sensor head. The

most suitable angle of the sensor head varies with the trans-

parent object. The angle of the sensor head can be, however,

0° or 45° for the smooth sensing of such transparent objects

due to the characteristic of polarized light. There is no need

for the angle to be midway between 0° and 45°. E39-L109,

which is sold separately, is a mounting bracket that rotates to

angles of 0° or 45° and enables E3X-NL to sense such trans-

parent objects smoothly with its sensing head set at 0° or 45°

without changing the sensing positive.

Fuzzy Teaching Function

E3X-NL in two-point teaching operation will perform fuzzy

computation using the difference in glossiness and the differ-

ence in light energy between the two teaching points to deter-

mine the thresholds setting with E3X-NL. As shown in the

following table, if there is only a small difference in glossiness

but there is a large difference in light energy between the two

teaching points, the thresholds set with E3X-NL will be deter-

mined by the light energy values.

Countermeasures against Teaching Errors Resulted with

Transparent Labels on Sheets

The material of the sheets must not be too glossy.

Nomenclature:

1,000

100

10

Object no.

1

23456789

10

1. White paper

2. Brown corrugated cardboard

3. Paper gummed tape

4. White glossy paper (individu-

al packages for OMRON

sensors)

5. Blue mount paper for label

6. Transparent label on blue

mount paper

7. Glossy plastic

8. Transparent glass (t=1 mm)

9. Gold printing ink (Gold part

of Cabin Mild Box)

10. Metal mirror surface (SUS

mirror surface)

Taught

Difference

in glossiness

between two

teaching points

Taught

Difference

in light energy

between two

teaching points

Discriminating method

Large

Large

Discriminated by glossiness.

Large

Small

Discriminated by glossiness.

Small

Large

Discriminated by light energy.

Small

Small

Discriminated by glossiness. A

teaching error will result if the dif-

ference in glossiness and that in

light energy are both less than the

sensing levels of E3X-NL.

(Example) Metal cylindrical object coated with transparent film

Metal cylindrical object

coated with

transparent film

Sensing head

The object can be sensed smoothly when the

angle of the sensing head is either 0˚ or 45˚.

45˚

Operation indicator

(orange)

Teaching button

Mode selector

Stability indicator

(green)

Teaching indicator

(red/green)

Operation mode

selector

Discriminated by glossiness

Fuzzy discrimination of glossiness and light energy

Discriminated by light energy

Difference in light energy

Large

Small

Teaching error