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EIZO’s Rugged LCD Monitors: Understanding the Hammer Shock Test

Have you ever wondered what makes a monitor truly “rugged”? Monitors used in defense and aerospace applications must meet the rigorous design specifications and testing requirements put in place by the United States Department of Defense (DoD) to ensure the LCD monitor can survive in the extreme environment where it is deployed.  The DoD defines the requirements specifications and associated testing criteria using military standards or “MIL-STD” as it is widely known. Military standards and design specifications help define standardization objectives, which are beneficial to ensuring products meet certain requirements for interoperability, commonality, reliability, total cost of ownership, compatibility with integrated systems, and other defense-related objectives.  

When making a ruggedized monitor, there are different approaches to how the product’s final design complies with the MIL-STD requirements. When a product manufacturer has complete design authority and the technical expertise to see a product through from conception to manufacturing to testing, it takes full control over the quality of those processes. When product development or some of its processes, including testing and validation, are outsourced to third-party facilities, quality control standards cannot be guaranteed. Furthermore, when a manufacturer specifies that their product is “designed to meet a standard”, this does not mean it is proven to comply with that standard. For rugged applications, it is important to identify manufacturers who fully qualify their products to ensure compliance to the required MIL-STD. 

MIL-DTL-901E High Impact Shock Test

MIL-DTL-901E is a detail (DTL) specification that defines high-impact (H.I.) shock testing requirements for machinery, equipment, systems, and structures on surface ships and submarines. Adopted on June 20, 2017, MIL-DTL-901E replaces MIL-S-901D as standard to verify the ability of onboard installations to withstand shock from nuclear and conventional weapons, as well as an environmental mechanical shock during operation.

MIL-DTL-901E has different levels of testing – lightweight (hammer weight: 400 lbs) performed on a lightweight shock machine (LWSM), medium weight (hammer weight: 3,000 lbs.) performed on a medium weight shock machine (MWSM), and a heavyweight or barge test (underwater test) performed on a floating shock platform. Items tested are categorized according to one of the following grades: 

Grade A: Items that are essential to the safety and continued combat capability of the ship.

Grade B: Items whose operation is not essential to the safety and combat capability of the ship, but which could become a hazard to personnel operating or manning Grade A equipment or to the ship as a whole, as a result of exposure to shock.

Grade A items support the ship’s safety and combat capacity; thus, it is essential that it is able to continue operation after exposure to shock. In other words, Grade A equipment should not fail under a MIL-DTL-901E type shock event. Whereas Grade B only qualifies an item for safety of the surrounding personnel and environment and does not guarantee continued operation after impact. A product which is shown to have passed or been tested just for MIL-DTL-901E does not mean that it meets Grade A.

Under MIL-DTL-901E, equipment is further categorized by classes defined by whether isolation devices (e.g., shock, noise, or vibration mounts, or flexible elements) are used in the installation. The classes are: 

Class I – Equipment required to meet the shock requirements without the use of isolation devices installed between the equipment and ship structures.

Class II – Equipment required to meet the shock requirements with the use of isolation devices installed between the equipment and ship structures.

Class III – This equipment class is defined as that which has shipboard application both with and without the use of resilient mounts and is therefore required to meet both Class I and Class II requirements.

As isolation devices vary in specification and configuration, when an item is tested for and passes with a Class II configuration, if the deployment does not reflect the same conditions as when the product was tested for MIL-DTL-901E, it is reasonable to expect that exposure to shock may not yield the same results in the target environment. This can complicate system installation if a product is not fully qualified to meet the exact configuration of the deployment. Since Class I product is able to meet the shock requirements without these isolation devices, it alleviates the configuration requirements of the system by reducing weight factors, required space for accommodating additional fixtures, and the costs of the additional devices. 

How In-House Design Achieves True Ruggedization

Generally, the larger an LCD monitor is, the more energy the components generate on impact, making it difficult for most large-size displays to counter high-impact shock. In this video, EIZO is conducting the MIL-DTL-901E Lightweight Hammer Shock Test: Grade A, Class I. This test is being performed on the Talon RGD3202W, a 32-inch 4K resolution rugged LCD monitor, with EIZO’s own staff overseeing the test. Every Talon model is tested for and passes the same Grade A, Class I conditions and configuration. 

The test is in accordance with the MIL-DTL-901E criteria for all 3 axis – X, Y and Z axis.  The testing setup is as follows:

  • Standard Shock Test Methods: Lightweight
  • Shock Grades: Grade A
  • Mounting: Deck Mounted
  • E.U.T Condition: Operational
  • Hammer Height: 5 ft (152.4 cm) / 3 ft (91.5 cm) / 1 ft (30.5 cm)

 

EIZO applies its 50+ years of expertise in designing and manufacturing visual technology in-house to ensure that the Talon line is able to pass the Grade A test for not only safety, but also continued operation in rugged environments. This is achieved thanks to decades of experience in designing everything from the PCB (printed circuit board) and components to each sensitive layer of the LCD itself. Ruggedization is a complex process which requires fine-tuning of all aspects of product’s design. For example, it is not enough to simply use tempered glass to reinforce a monitor for rugged use. EIZO engineers use CAE (Computer Aided Engineering) simulation and in-depth analysis of the entire mechanical design, including screw attachment points, to ensure not only the glass, but all parts of the monitor are able to endure required shock levels. The product design is then fully realized after repeated simulation and testing to ensure the final result is optimized for rugged use. Below illustrates how EIZO uses CAE to conduct a simulation. 

Example of CAE simulation for a Talon monitor conducted by EIZO engineers.

Though structural simulations for monitors are not uncommon for many vendors, they are often only partial simulations or utilize simplified versions of the models to reduce the number of calculations needed to conduct the test. However, this creates a gap that does not fully consider all aspects of the product’s composition and does not allow for an accurate assessment of its ability to pass rigorous MIL standard testing. EIZO conducts CAE for the entire structure of its Talon monitors to ensure every model is capable of MIL compliance prior to the actual test. 

Furthermore, EIZO conducts simulations without a shock absorber, or isolation device, to ensure that the monitor is able to withstand shock in, for example, a configuration where it is attached directly to the ship structure. This ensures the monitors meet shock requirements without needing to overhaul the configuration or retest for specific shock conditions in the target deployment.

Since EIZO’s products are developed and manufactured in-house, we are able to design every Talon rugged monitor with ruggedization in mind from the outset. This allows us to not only take full control of the quality of production, but EIZO’s in-house engineers are able to address challenges that occur during testing and immediately draw up a plan to counter them.

In-house development of Talon monitors: PCB and circuitry, LCD unit production, and assembly.

True Rugged LCD Monitors for Rugged Systems

EIZO’s Talon rugged LCD monitors, ranging in size from 21” to 32”, are fully qualified for vibration, shock, humidity, decompression, and extreme temperature testing and pass MIL-STD-810, MIL-STD-461, and MIL-DTL-901E (Grade A, Class I) standards. EIZO rugged monitors also offer optical bonding which provides extra durability for shock and environmental protection, prevents humidity and condensation in between the optical layers, and improves image quality by omitting light reflections between the LCD and front filter. In addition, the EIZO Talon series offers often required options such as sunlight readability, NVIS filters, water resistance with IP65 (front), built-in heaters, conformal coating to protect components, and integrated keyboard, mouse, and dynamic touch switching between up to four simultaneous inputs.  

While many monitors in the market are promoted as “rugged”, not all are proven for use in extreme environments according to MIL standards. EIZO remains committed to providing proven solutions that are achieved through in-house development, manufacturing, and rigorous testing for rugged applications with its own staff overseeing the entire production chain. Stable sourcing based on over 50 years of relationships with key suppliers also ensures long-term availability, component quality control, and extended lifecycle support. EIZO develops innovative visual solutions for mission-critical markets worldwide including defense, military, air traffic control, maritime, healthcare, industrial, and more. Rugged by design, Talon monitors are the reliable choice for military missions across land, in the air, at sea, or in space.

To learn more information about the MIL-DTL901E testing specifications, you can access the official PDF document here

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