LED Measurement System User Manual

Please select the correct version of the user manual for your LED Measurement System. You can find the model number on the sticker on the base of your unit.

Ossila LED Measurement System User Manual L2005A3 (PDF)

Ossila OLED Lifetime System L2005A2 User Manual (PDF)

LED Measurement System

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1. Overview

The Ossila LED Measurement System is a low-cost solution for reliable current-voltage-luminance measurements of light emitting diodes. The system is controlled by specially designed software which can perform multiple IVL measurements and measure the current, luminance, and efficiency over long periods of time.

2. EU Declaration of Conformity (DoC)

We

declare that the DoC is issued under our sole responsibility and belongs to the following product:

Object of Declaration

Ossila LED Measurement System (T2005A3/T2005B3/T2005C3/T2005E3)

The object of declaration described above is in conformity with the relevant Union harmonisation legislation:

Signed:

Name: Dr James Kingsley

Place: Leiden

Date: 16/11/2021

3. Safety

3.1 Use of Equipment

The Ossila LED Measurement System is designed to be used as instructed. It is intended for use under the following conditions:

• Indoors in a laboratory environment (pollution degree 2).
• Altitudes up to 2000 m.
• Temperatures of 5°C to 40°C; maximum relative humidity of 80% up to 31°C.

The unit is supplied with a 24 VDC power adapter, in accordance with European Commission regulations and British Standards. Use of any other electrical power cables, adaptors, or transformers is not recommended.

3.2 Hazard Icons

The following symbols can be found at points throughout the rest of the manual. Note and read each warning before attempting any associated operations associated with it:

Table 3.1 Hazard warning labels used in this manual.

Symbol	Associated Hazard
	Electrical shock

3.3 General Hazards

Before installing or operating the Ossila LED Measurement System there are several health and safety precautions which must be followed and executed to ensure safe installation and operation.

3.4 Power Cord Safety

Emergency power disconnect options: use the power cord as a disconnecting method and remove from wall. To facilitate disconnect, make sure the power outlet for this cord is readily accessible to the operator.

3.5 Servicing

If servicing is required, please return the unit to Ossila Ltd. The warranty will be invalidated if:

• Modification or service has been carried out by anyone other than an Ossila engineer.
• The Unit has been subjected to chemical damage through improper use.
• The Unit has been operated outside the usage parameters stated in the user documentation associated with the Unit.
• The Unit has been rendered inoperable through accident, misuse, contamination, improper maintenance, modification, or other external causes.

3.6 Health and Safety - Servicing

Servicing should only be performed by an Ossila engineer. Any modification or alteration may damage the equipment, cause injury, or death. It will also void your equipment’s warranty.

4. Requirements

Table 4.1 details the power requirements for the Ossila LED Measurement System, and the minimum computer specifications for the Ossila LED IVL software.

Table 4.1 Ossila LED Measurement System requirements.

5. Unpacking

5.1 Packing List

The standard items included with the Ossila LED Measurement System are:

• The Ossila LED Measurement System.
• 24 VDC power adapter.
• USB-B cable.
• USB memory stick pre-loaded with the user manual, USB drivers, quality control data, and software installer.
• Resistor test device.

5.2 Damage Inspection

Examine the components for evidence of shipping damage. If damage has occurred, please contact Ossila directly for further action. The shipping packaging will come with a shock indicator to show if there has been any mishandling of the package during transportation.

6. Specifications

The Ossila LED Measurement System specifications are shown in Table 6.1.

Table 6.1 Ossila LED Measurement System specifications.

7. System Components

The Ossila LED Measurement System is comprised of three items: the Ossila LED Measurement System (Figure 7.1), and the Ossila LED IVL Software (Figure 7.2).

8. Installation

1. Install the Ossila LED IVL software on your PC.
1. Run the file ‘Ossila-LED-IVL-Installer-X-X-X-X.exe’ on the USB memory stick provided.
2. Follow the on-screen instructions to install the software.
2. Connect the 24 VDC power adaptor to the power socket on the rear of the unit.
3. Connect the unit to your PC using the provided USB-B cable, or an Ethernet cable if preferred.

If the unit is not detected, or driver installation fails, please refer to the SMU USB Driver Installation Guide found on the USB memory stick.

9. Operation

9.1 Measurement Types

The Ossila LED IVL software can perform 2 different types of measurements. Each measurement type can be selected using the tabs at the top of the window. The available measurements are:

1. Characterisation (Section 9.1.1).
2. Lifetime (Section 9.1.2).

Each measurement type requires several settings to be selected before it can be performed. Settings that are shared between all measurements are detailed in Section 9.3. Measurement specific settings are detailed in Sections 9.3.3, and 9.3.4

9.1.1 Characterisation

The Characterisation tab is used to perform I-V measurements of LEDs, whilst measuring the illuminance, luminance, white count, and current and power efficiencies using the built-in light sensors.

The Lifetime tab is used to perform long-term measurements of LEDs by holding them at a specified voltage and periodically measuring the current of the LED and response of the light sensors.

9.2 Quick Start Guide

1. Start the Ossila LED IVL software. The window shown in Figure 9.1 will open.
2. Choose a measurement type as described in Section 9.1.
3. Place your device in the device holder and close the lid.
4. Set the appropriate settings in the software (explained in more detail in Section 9.3).
5. Click the ‘Measure’ button.
1. For each pixel, measurements are performed using the chosen measurement settings.
2. Data is plotted as it is measured, using a solid line for primary (left) y-axis and a dashed line for the secondary (right) y-axis.
3. This process is repeated until all pixels have been measured.
6. If automatic saving is turned on, the measurement data and settings will then be saved.

9.3 Software Settings

There are several settings in the program which must be filled in before taking a measurement. These are found in the column on the left of the window, as shown in Figure 9.1.

9.3.1 System Settings

(I) System Address

Select the COM port or IP address of the connected unit you intend to use (USB and Ethernet connection respectively). This box will be populated automatically with the addresses of any units connected to the computer or network.

(II) Current Range

Select the range of current values to be used for the measurement. This defines the upper limit and accuracy of current measurements that can be performed by the unit. The values for each range are given in Table 9.1.

Table 9.1 Current range specifications of the Ossila LED Measurement System.

(III) Lux Range

Select the range of lux values to be used for the measurement. This defines the upper limit and resolution of lux measurements that can be performed by the unit. The values for each range are given in Table 9.2.

Table 9.2 Lux range specifications for the Ossila LED Measurement System.

(IV) Sampling Rate

Select the number of samples to be taken for each data point. A higher number of samples per point will improve the accuracy and precision of the measurement. However, this will increase the time taken for the measurement to be performed.

9.3.2 Device Settings

(I) Pixels to Measure

Select which pixels to measure. Pixel numbers are labelled on the device holder. Selection boxes will be enabled and disabled based upon the device holder being used.

(II) Pixel Area

Set the area in cm² of each pixel of the device.

(III) Inverted Device

Set whether the device to be measured is inverted. This option should be on if the anode of your device connects to the ‘cathode’ pins in the device holder.

9.3.3 Characterisation Settings

(I) Measure Luminance

Set whether measurements of the device’s light output will be performed. If set to ‘Off’, the system will not check that the lid is closed before measuring.

(II) Start Voltage

Set the voltage in volts at which to start the current-voltage measurement. This can be set between -10 V and +10 V.

(III) End Voltage

Set the voltage in volts at which to end the current-voltage measurement. This can be set between -10 V and +10 V.

(IV) Voltage Increment

Set the step size in volts for changing the voltage during current-voltage measurement.

(V) Voltage Settle Time

Set the time in seconds between applying a voltage and measuring the current. The minimum value is dependant on the selected lux range:

• 0 s for 100 klx
• 0.05 s for 5000 lx
• 0.4 s for 500 lx

(VI) Hysteresis I-V

This option performs a reverse current-voltage measurement after the forward currentvoltage measurement has completed. This reverses the set start and end voltages and uses the same voltage increment and settle time as the forward measurement.

9.3.4 Lifetime Settings

(I) Duration

Set the total duration in hours for the lifetime measurement.

(II) Interval

Set the time interval in minutes between performing repeat measurements of the device.

(III) Hold Voltage

Set the voltage that all pixels will be held at between measurements. This can be set between -10 V and +10 V.

(IV) Primary Axis Units

Set which property is plotted on the primary (left) y-axis.

(V) Secondary Axis Units

Set which property is plotted on the secondary (right) y-axis.

9.3.5 Saving and Loading Settings

(I) Save Settings

Saves the current settings as a profile that can be loaded quickly for use at another time. When clicked, you will be prompted to name the settings profile.

• If the name is already in use, you will be asked if you wish to overwrite the previous profile.
• The name cannot contain the characters: \ / : * ? “ < > |

The settings profile will be added to the drop-down box using the given name.

(II) Settings Profile

Select a saved settings profile from the drop-down box. The settings fields will be populated with the saved values from the selected profile.

Settings profiles can be deleted by selecting the profile and then clicking the red ‘delete’ icon next to the drop-down box.

9.3.6 Measurement Controls

(I) Measure

Clicking this button will start the measurement using the chosen settings. This button cannot be clicked if the software has not detected a unit.

(II) Abort

Stops a measurement that is currently in progress.

9.3.7 Plot Controls

(I) Plot Display Controls

By default, the axes of the plot will automatically scale to display all the data within it. The view can be controlled manually using the following mouse controls:

• Left/Middle click and drag – pan the axes.
• Right click and drag – scale the axes (left-right for x-axis, up-down for y-axis).
• Scroll wheel – scale the axes centred on the cursor location.

A specific axis can be controlled by using these controls on the axis labels. The axes can be reset by clicking the “Reset View” button shown in Figure 9.9.

(II) Axis Selection

In the characterisation tab the data plotted on the primary and secondary y-axes can be selected using the drop-down boxes beneath the axes. Axes cannot be changed whilst a measurement is being performed.

(III) Show Primary Axis

Controls whether the data plotted on the primary (left) y-axis is displayed.

(IV) Show Secondary Axis

Controls whether the data plotted on the secondary (right) y-axis is displayed.

9.3.8 Saving Data

(I) Save After Measurement

The program allows for data to be saved automatically, as well as manually once the measurement is complete. For automatic saving, the ‘Save Directory’ and ‘Device Label’ fields must be filled in before the measurement can start, these are detailed below.

(II) Save Directory

Sets the location in which to save the results. This can be set either by:

• Manually typing the directory into the field.
• Copying and pasting it from your file explorer.
• Clicking the folder icon in the field, which will open a dialog box to allow the selection of a folder to save to.

(III) Device Label

Sets the name of the comma-separated values (.csv) files in which data will be saved.

The field cannot contain the following characters: \ / : * ? “ < > |

(IV) Save Data

Clicking this button will manually save the measurement results of the active curve.

(V) Save Data Format

Data for each pixel is saved to a separate .csv file, with the following columns:

• Time (s) - (lifetime only)
• Voltage (V)
• Current (A)
• Illuminance (lx)
• Luminance (cd/m²)
• White Count
• Current Efficiency (cd/A)
• Power Efficiency (lm/W)

The settings used for a measurement are saved to a separate .csv file in a ‘Settings’ folder in the selected save directory. If this folder does not exist, it will be created.

10. Test Device

The system is shipped with a pair of test devices that can be used to verify the correct operation of the system. One has 100 kΩ resistors that can be used to check the calibration of the system. The other has semiconductor LEDs to test the response of the light sensors. Both are arranged in the geometry of the substrate pixels, and the appearance of the test device will depend on the substrate system being used.

10.1 Taking a Measurement

1. Plug in and switch on the system.
2. Allow at least 30 minutes for the system to warm up.
3. Place the test device in the device holder with the resistors facing upwards.
4. Start the LED IVL software and enter the following settings in Figure 10.2.
1. These settings can be used with any current range except for the 20 μA range. For this range the start and end voltages must be lowered to -2 V and 2 V respectively.
2. The ‘Pixels to Measure’ checkboxes should match the device configuration you have.

1. Click the ‘Measure’ button.
2. The system should measure straight line resistor responses from -100 μA to 100 μA (or - 20 μA to 20 μA for the 20 μA current range) as shown in Figure 10.3.
3. To check the calibration of the system, use the I-V data to calculate the measured resistance at -10 and 10 V (-2 and 2 V for the 20 μA current range).
1. Resistance can be calculated using: R = V / I
2. For the 200 mA current range the calculated resistance should be between 98 and 102 kΩ (within 2% of the resistor value).
3. For all other ranges the calculated resistance should be between 99 and 101 kΩ (within 1% of the resistor value).

11. Troubleshooting

Most of the issues that may arise will be detailed here. However, if you encounter any issues that are not detailed here, then please contact Ossila.

11.1 Installation and Setup

11.2 Error Messages and Warnings

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