Light shield

A method to reduce the interference of light in a multi-shelf merchandise display unit from shelves above a shelf on which stock levels are being measured, in which the unit includes

• a plurality of sensors mounted on a wall of the unit, in which each sensor corresponds to and is associated with a single shelf and in which the shelves are at least semi-porous to the illumination, wherein the unit further comprises a sensor shield attached to the wall of the unit above each sensor;
• wherein the shield comprising:
• a plate having a shape that is sufficient substantially to reduce or prevent incident illumination from a shelf above from reaching the sensor,
• the plate being attachable to casing of or around the sensor or the wall of the unit and above the shelf with which the sensor is associated,
• wherein the plate is opaque to the illumination detected by the sensor,
• wherein the plate has a length that intersects a virtual line between the lowest point of the sensor when in situ and a point on the shelf immediately above that is furthest from the sensor to block or reduce incident or ambient light on the sensor, and wherein the sensors are mounted on the wall of the unit opposite a source of illumination.

A method in a multi-shelf merchandise display unit, the method comprising

• measuring a level of illumination entering or originating from within the unit, wherein the level of illumination is measured by a plurality of sensors positioned on an opposite side of stock placed in the unit to a source of illumination, and
• wherein a sensor shield is attached above each sensor;
• in which each sensor corresponds to and is associated with a single shelf and in which the shelves are at least semi-porous to the illumination, the shield comprising:
• a plate having a shape that is sufficient substantially to reduce or prevent incident illumination from a shelf above from reaching the sensor,
• the plate being attachable to casing of or around the sensor or the wall of the unit and above the shelf with which the sensor is associated,
• wherein the plate is opaque to the illumination detected by the sensor,
• wherein the plate has a length that intersects a virtual line between the lowest point of the sensor when in situ and a point on the shelf immediately above that is furthest from the sensor to block or reduce incident or ambient light on the sensor, and wherein the sensors are mounted on the wall of the unit opposite a source of illumination.

A sensor shield in a multi-shelf merchandise display unit including a plurality of sensors mounted on a wall of the unit in which each sensor corresponds to and is associated with a single shelf of said display unit and in which the shelves are at least semi-porous to the illumination, the shield comprising:

• a plate having a length or shape that is sufficient substantially to reduce or prevent incident illumination from a shelf above from reaching the sensor associated with the shield, the plate being attachable to casing of or around the sensor or the wall of the unit,
• wherein the plate is opaque to the illumination detected by the sensor,
• wherein the plate has a length that intersects a virtual line between the lowest point of the sensor when in situ and a point on a shelf immediately above that is furthest from the sensor to block or reduce incident or ambient light on the sensor,
• wherein the plate has a quadrant or semicircular shape, and
• wherein the sensors are mounted on the wall of the unit opposite a source of illumination and wherein the source of illumination is on an opposite side of said display unit to said sensors.