The Outdoor Touch Screen
Using the IR Touch Screens in an outdoor environment requires the specific technologies to reduce sunlight interference. A worthy touch screen should not be affected by weather factors such as snow, heavy rain, strong winds and humidity. Also, it should eliminate sunlight interference and protect against water or dust as it is more suitable for the outdoor environments and more convenient for the use with IR Touch screens.
What are our state of art technologies applied to the outdoor environments?
To eliminate sunlight interference in outdoor environments, we have used the innovative optical filter technologies. These state of the art filter technologies will eliminate sunlight interferences and provide multi-touch operations in the outdoor environment.
The three filters we used follow:
- Anti-Solar Filter is the polarized filter removing the direct sunlight, which is incoming to the IR sensor plane of the touch panel. This anti-solar filter provides an excellent uniformity.
- Sun-Block Filter removes any reflected and refracted light which is inside the touch module frame. It also helps to get over reflection and refraction phenomenon from the glass.
- Front IR Filter removes lower wavelength of sunlight and improves the transmissivity of IR LED’s wavelength
Overall, these technologies maximize the efficiency of the IR Touch Screens.
How to secure the required Signal to Noise ratio(S/N) in outdoor IR touch environments
To secure the required S/N ratio in the outdoor environment is one of the most important technologies.
The stronger the sunlight interference, the worse the S/N ratio becomes. The failure rate of the Touch function will increase if the S/N ratio of the Touch module deteriorates.
Thus, the technologies applied to IRON provide a stable touch function in the outdoor environment by ensuring S/N ratio.
As mentioned above, there are two main causes making noises. One is the interference from the sunlight and the other is from the circuit of the PCBA Board. In other words, it is important to have the S / N required for IR sensor technologies, and engineers should consider reducing these overall noise intensities in outdoor environments.
The PCB circuit should be also designed to reduce noise, and the impedance of the IR signal as well as the low noise power-line design should also be considered.
Based on the above-mentioned basis, IRON was designed by securing the required S/N ratio for multi-touch operation in the outdoor environment. At the same time, special filters applied to IRON, optimized flame and PCB design contributed to ensuring a satisfactory S/N ratio.
＊Required S/N: Minimum Signal to Noise ratio to perform a Multi-Touch Functions
Higher Protection level with creative design of frame
- IRON is satisfied with IP65(standard) and IP66(option) protection level.
- Aluminum extruded one-body frame structure of touch module makes it have price competitiveness and increase yield rate.
- We ensure the simple the design of the IP65 frame which is including a protection rubber assembly is the best frame for outdoor touch module.
A. Extruded one-body Frame structure
• Extruded one-body type can minimize the number of frame connection.
• By minimizing connection, water and dust can be prevented effectively.
B. Rubber Protection
• By inserting the rubber between IR filters mounted in the frame, the waterproof capability is maximized.
• It is made of materials that can operate in outdoor climate change environments
Operation free regardless any environment.
Regardless of the location of the Sun, Sunlight is the most powerful interference source.
Various directional interference of sunlight is the biggest obstacles to use in the outdoor environment.
Outdoor touch modules should be ready to protect in any directional and simultaneous interference environment.
A. As the position of sun, many interference factors affect the touch system
• As the sun changes position, touch module may be affected simultaneously by sunlight from various direction and reflections, refractions, and direct incident rays provide all possibility to interfere with the touch module.
The system will be affected when the sun is located on the side or top of the touchscreen, or when sunlight is reflected from a wall of a building or moving vehicles.
B. The Quantity change of interference factors
• When the sun is located on the side of the touchscreen
- wall or glass of building(higher)
- bottom side (medium)
- moving vehicles (lower)
• When the sun is located on top of the touchscreen
- bottom side (higher)
- wall or glass of building (medium)
- moving vehicles (lower)
C. The combination of three filters is the best way to protect against sunlight invasion.
• The combination of three filters mounted in IRON can prevent sunlight from all directions.
• Regardless of the location of the sun, IRON always decreases sunlight interference.
How to verify the performance of outdoor IR touch?
Conditions to be considered when testing.
Place the Touch Module to be tested where various interferences are caused by sunlight such as direct, reflected and refracted sunlight. Angles with the face of the Touch Module relative to the sunlight are gradually changed horizontally or vertically. To measure the exact sunlight interference, direct light from sunlight, reflection or refraction in the surrounding environment must be considered.
At last, you can test the combined Glass and Touch Module together.
Things to consider during testing
The Touch Durability Test for interference from sunlight must simultaneously measure all the light generated interference from the IR sensor surface and consider the Multi-Touch function in such an interference environment.
Procedure of the test (Touch Durability in Sunlight Interference)
Unfortunately, there is no standard to demonstrate and measure performance for outdoor touch products to date. However, we have established guidelines for the testing methods and verification procedures based on our existing know-how founded on common sense.
How to Measure Minimum Facing Angle(MFA) and Power of Sun Light
- Place the Touch Module on the test stand, and the test stand should be made of rigid material.
- Adjust the tilt angle using the tilting controller on the test stand. If the multi-function cannot be used, stop the adjustment and Keep the Multi-Touch Function enabled.
When the IR sensors in the IR arrayed planes are directed to the Sun, the Incident Angle can be thought of as the Minimum Facing Angle(MFA) when the IR sensors in the IR arrayed planes are directed to the Sun
- Use a Solar Angle Measuring Instrument (SAMI) to measure the minimum facing angle and you can automatically measure the incident angle of Sun Light by SAMI. Also, you can use the Solar Power Meter, or Optical Signal Generator (OSG), to measure Solar Incident Power entering the IR sensor plane. Solar Angle Measuring Instrument (SAMI), a measuring instrument like this, will be released separately.
- After measuring the Minimum Facing Angle (MFA), move the direction of the Touch Module to the left or right to measure the angle while the Multi-Touch Function is operating normally. This normal operational conditions may vary depending on the Multi-Touch function and consumers need.
This method for testing is very reasonable for the reliability test of the outdoor IR Touch module.
6635 Badura Ave. #120
Las Vegas, NV 89118
Kwangmyeong Techno Park #B-1403,
Kwangmyeong-Si, Gyeonggi-Do 14322
Republic of Korea
Langguang Technology Park, #A311,
Nanshan District, Shenzhen 518000
People's Republic of China