heat tolerance of an lcd touch screen free sample

Liquid crystal displays (LCD) have become an essential component to the industry of display technology. Involved in a variety of contexts beyond the indoors like LCD TVs and home/office automation devices, the LCD has expanded its usage to many environments, such as cars and digital signage, and, thus, many temperature variations as well.

As with any substance that requires a specific molecular characteristic or behavior, LCDs have an operating temperature range in which the device, if within, can continue to function properly and well. In addition to that, there is also an ideal storage temperature range to preserve the device until used.

This operating temperature range affects the electronic portion within the device, seen as falling outside the range can cause LCD technology to overheat in hot temperatures or slow down in the cold. As for the liquid crystal layer, it can deteriorate if put in high heat, rendering it and the display itself defective.

In order for the LCD panel to avoid defects, a standard commercial LCD’s operation range and storage range should be kept in mind. Without adaptive features, a typical LCD TV has an operating range from its cold limit of 0°C (32°F) to its heat limit of 50°C (122°F) (other LCD devices’ ranges may vary a bit from these numbers).

The storage range is a bit wider, from -20°C (-4°F) to 60°C (140°F). Though these ranges are quite reasonable for many indoor and even outdoor areas, there are also quite a few regions where temperatures can drop below 0°C or rise above 32°C, and in these conditions, LCDs must be adapted to ensure functionality.

Heat, can greatly affect the electronics and liquid crystals under an LCD screen. In consideration of heat, both external heat and internally generated heat must be taken into consideration.

Seen as the liquid crystals are manipulated in a device by altering their orientations and alignments, heat can disrupt this by randomizing what is meant to be controlled. If this happens, the LCD electronics cannot command a certain formation of the liquid crystal layer under a pixel, and the LED backlighting will not pass through as expected, which can often lead to dark spots, if not an entirely dark image. This inevitably disrupts the display’s readability.

Depending on the upper limit of the operation temperature range, LCD device can be permanently damaged by extreme heat. With long exposure to extreme heat, besides the destruction of the liquid crystals, battery life can shorten, hardware can crack or even melt, response time may slow to prevent even more heat generation from the device.

The LED backlight and the internal circuitry, typically TFT-based in the common TFT LCDs, are components that can generate heat that damages the device and its display. To address this concern with overheating, many devices use cooling fans paired with vents.

Some devices that are used in extremely high ambient temperatures may even require air conditioning. With air vents to carry the heat out, the device can expel it into the surroundings.

But this leads to another problem: how can moisture be prevented from entering through the vent? If moisture enters the device and high heat is present, condensation can occur, fogging the display from inside, and in some cases, short-circuiting may cause the device to turn off. In order to circumvent this issue, the shapes of the air vents are specific in a way that allows only for air movement, not forms of moisture.

In the opposite direction is extreme cold. What typically occurs in the cold is “ghosting” (the burning of an image in the screen through discoloration) and the gradual slowing and lagging of response times. Like heat-affected LCD modules, the extreme temperature can affect the liquid crystals. This layer is a medium between the liquid and solid state, so it is still susceptible to freezing.

An LCD device can be left in freezing temperatures because it will likely not be permanently damaged like in the heat, but it is important to understand the device’s limits and how to take precautions when storing the device. The standard and most common lower-bound storage range limit is -20°C, below freezing, but if possible, it would be best to keep it above that limit, or else there is still a risk of permanent damage.

If the device is not adapted for the cold, it would be good to keep it bundled up, trapping the heat within layers. However, this is only a temporary solution. Adapted, rugged devices have advantages such as screen enclosure insulation for heat level preservation and, in more extreme cases, heaters to generate extra heat to raise the internal temperature to a level above the minimum.

When selecting the appropriate module, it is necessary to understand the device’s expected primary application. The application will decide factors such as display type, environmental conditions, whether or not power consumption is a factor, and the balance between performance and cost. These factors can have an effect on the operation and storage temperature ranges for the device.

Display types have a lot of variation. Choices like alphanumeric or graphic LCD, human-machine interactive LCD modules and touchscreen panels capabilities, the width of the viewing angle, level of contrast ratios, types of backlighting, and liquid crystal alignment methods are often considered. For example, the twisted nematic LCD provides for the fastest response time at the lowest cost, but cannot offer the highest contrast ratio or widest viewing angle.

Environment-based factors must consider things besides the obvious temperature like UV exposure and humidity/moisture, as they all are necessary in finding the perfect fit extreme temperature LCD module.

Besides the LCD modules, recent new products have opened doors in wide temperature range displays, such as OLED displays. OLED displays offer better displays in regard to contrast, brightness, response times, viewing angles, and even power consumption in comparison to traditional LCD displays.

These benefits, in addition to its ability to achieve a wide temperature range, provide more options for consumers in search of high quality displays for extreme climates.

If using a High Brightness Display, you can choose the AD Board which have light sensor function that can adjust panel"s brightness automatically.RTP touch supports light gloves and stylus touch (need to adjust the firmware),

The use of liquid crystal displays (LCDs) in user interface assemblies is widespread across nearly all industries, locations, and operating environments. Over the last 20 years, the cost of LCD displays has significantly dropped, allowing for this technology to be incorporated into many of the everyday devices we rely on.

The odds are high you are reading this blog post on a laptop or tablet, and it’s likely the actual screen uses LCD technology to render the image onto a low-profile pane of glass. Reach into your pocket. Yes, that smartphone likely uses LCD technology for the screen. As you enter your car, does your dashboard come alive with a complex user interface? What about the menu at your favorite local drive-thru restaurant? These are some everyday examples of the widespread use of LCD technology.

But did you know that the U.S. military is using LCD displays to improve the ability of our warfighters to interact with their equipment? In hospitals around the world, lifesaving medical devices are monitored and controlled by an LCD touchscreen interface. Maritime GPS and navigation systems provide real-time location, heading, and speed information to captains while on the high seas. It’s clear that people’s lives depend on these devices operating in a range of environments.

As the use of LCDs continues to expand, and larger screen sizes become even less expensive, one inherent flaw of LCDs remains: LCD pixels behave poorly at low temperatures. For some applications, LCD displays will not operate whatsoever at low temperatures. This is important because for mil-aero applications, outdoor consumer products, automobiles, or anywhere the temperature is below freezing, the LCD crystal’s performance will begin to deteriorate. If the LCD display exhibits poor color viewing, sluggish resolution, or even worse, permanently damaged pixels, this will limit the ability to use LCD technologies in frigid environments. To address this, there are several design measures that can be explored to minimize the impact of low temperatures on LCDs.

Most LCD displays utilize pixels known as TFT (Thin-Film-Transistor) Color Liquid Crystals, which are the backbone to the billions of LCD screens in use today. Since the individual pixels utilize a fluid-like crystal material as the ambient temperature is reduced, this fluid will become more viscous compromising performance. For many LCD displays, temperatures below 0°C represent the point where performance degrades.

Have you tried to use your smartphone while skiing or ice fishing? What about those of you living in the northern latitudes - have you accidently left your phone in your car overnight where the temperatures drop well below freezing? You may have noticed a sluggish screen response, poor contrast with certain colors, or even worse permanent damage to your screen. While this is normal, it’s certainly a nuisance. As a design engineer, the goal is to select an LCD technology that offers the best performance at the desired temperature range. If your LCD display is required to operate at temperatures below freezing, review the manufacturer’s data sheets for both the operating and storage temperature ranges. Listed below are two different off-the-shelf LCD displays, each with different temperature ratings. It should be noted that there are limited options for off-the-shelf displays with resilience to extreme low temperatures.

For many military applications, in order to comply with the various mil standards a product must be rated for -30°C operational temperature and -51°C storage temperature. The question remains: how can you operate an LCD display at -30°C if the product is only rated for -20°C operating temperature? The answer is to use a heat source to raise the display temperature to an acceptable range. If there is an adjacent motor or another device that generates heat, this alone may be enough to warm the display. If not, a dedicated low-profile heater is an excellent option to consider.

Made of an etched layer of steel and enveloped in an electrically insulating material, a flat flexible polyimide heater is an excellent option where space and power are limited. These devices behave as resistive heaters and can operate off a wide range of voltages all the way up to 120V. These heaters can also function with both AC and DC power sources. Their heat output is typically characterized by watts per unit area and must be sized to the product specifications. These heaters can also be affixed with a pressure sensitive adhesive on the rear, allowing them to be “glued” to any surface. The flying leads off the heater can be further customized to support any type of custom interconnect. A full-service manufacturing partner like Epec can help develop a custom solution for any LCD application that requires a custom low-profile heater.

With no thermal mass to dissipate the heat, polyimide heaters can reach temperatures in excess of 100°C in less than a few minutes of operation. Incorporating a heater by itself is not enough to manage the low temperature effects on an LCD display. What if the heater is improperly sized and damages the LCD display? What happens if the heater remains on too long and damages other components in your system? Just like the thermostat in your home, it’s important to incorporate a real-temp temperature sensing feedback loop to control the on/off function of the heater.

The first step is to select temperature sensors that can be affixed to the display while being small enough to fit within a restricted envelope. Thermistors, thermocouples, or RTDs are all options to consider since they represent relatively low-cost and high-reliability ways to measure the display’s surface temperature. These types of sensors also provide an electrical output that can be calibrated for the desired temperature range.

The next step is to determine the number of temperature sensors and their approximate location on the display. It’s recommended that a minimum of two temperature sensors be used to control the heater. By using multiple sensors, this provides the circuit redundancy and allows for a weighted average of the temperature measurement to mitigate non-uniform heating. Depending on the temperature sensors location, and the thermal mass of the materials involved, the control loop can be optimized to properly control the on/off function of the heater.

Another important consideration when selecting a temperature sensor is how to mount the individual sensors onto the display. Most LCD displays are designed with a sheet metal backer that serves as an ideal surface to mount the temperature sensors. There are several types of thermally conductive epoxies that provide a robust and cost-effective way to affix the delicate items onto the display. Since there are several types of epoxies to choose from, it’s important to use a compound with the appropriate working life and cure time.

For example, if you are kitting 20 LCD displays and the working life of the thermal epoxy is 8 minutes, you may find yourself struggling to complete the project before the epoxy begins to harden.

Before building any type of prototype LCD heater assembly, it’s important to carefully study the heat transfer of the system. Heat will be generated by the flexible polyimide heater and then will transfer to the LCD display and other parts of the system. Although heat will radiate, convect, and be conducted away from the heater, the primary type of heat transfer will be through conduction. This is important because if your heater is touching a large heat sink (ex. aluminum chassis), this will impact the ability of the heater to warm your LCD display as heat will be drawn toward the heat sink.

Insulating materials, air gaps, or other means can be incorporated in the design to manage the way heat travels throughout your system on the way toward an eventual “steady state” condition. During development, prototypes can be built with numerous temperature sensors to map the heat transfer, allowing for the optimal placement of temperature sensors, an adequately sized heater, and a properly controlled feedback loop.

Before freezing the design (no pun intended) on any project that requires an LCD display to operate at low temperatures, it’s critical to perform low temperature first. This type of testing usually involves a thermal chamber, a way to operate the system, and a means to measure the temperature vs time. Most thermal chambers provide an access port or other means to snake wires into the chamber without compromising performance. This way, power can be supplied to the heater and display, while data can be captured from the temperature sensors.

The first objective of the low-temperature testing is to determine the actual effects of cold exposure on the LCD display itself. Does the LCD display function at cold? Are certain colors more impacted by the cold than others? How sluggish is the screen? Does the LCD display performance improve once the system is returned to ambient conditions? These are all significant and appropriate questions and nearly impossible to answer without actual testing.

As LCD displays continue to be a critical part of our society, their use will become even more widespread. Costs will continue to decrease with larger and larger screens being launched into production every year. This means there will be more applications that require their operation in extreme environments, including the low-temperature regions of the world. By incorporating design measures to mitigate the effects of cold on LCD displays, they can be used virtually anywhere. But this doesn’t come easy. Engineers must understand the design limitations and ways to address the overarching design challenges.

A full-service manufacturing partner like Epec offers a high-value solution to be able to design, develop, and manufacture systems that push the limits of off-the-shelf hardware like LCD displays. This fact helps lower the effective program cost and decreases the time to market for any high-risk development project.

Noritake’s electronics division has been around since the creation of the Vacuum Fluorescent Display(VFD). We have grown to provide a wide array of products and services to ensure a smooth and efficient development cycle for your application. Our customer support staff will gladly provide you with technical support to assist with your needs.

We offer an expanding set of support tools for each of our product series, including code libraries and design programs. These tools work to accelerate the evaluation and integration procedures in order to have your prototype up and running as quickly as possible.

We are very aware of how important long-term support is for our customers and continue to strive to maintain a strong supply chain. Please see our GT Series Long Term Supply Policy.

Because of its transparency and thinness, it can be incorporated into LCD module, such as between liquid crystal and backlight, and between touch panel and liquid crystal.

We support you from the product design stage. We will customize the design such as heater size & shape, wiring, and temperature control, according to the customer’s request.

Whether supplying the heater film alone or as part of the module including the laminated cover glass, touch sensor and LCD display Nissha can support. Our project and QA management experience for film touch sensor programs seamlessly extends to the inclusion of optically clear film heater from development through to mass production.

While coordinating between the technical department and the sales department, information such as material design, process technology, and cost adequacy will be organized and it will be examined whether it can be entrusted.

The team is made up of members selected from each of the technical development, design, production technology, evaluation technology, and quality assurance departments, and plans for mass production.

We perform mass production suitability evaluation, failure mode analysis, reliability evaluation, etc., and confirm the optimal mass production conditions.

After preparing the mass production transfer document based on the results of the prototype verification, the project is transferred to the mass production department and mass production is started.

After mass production, the quality assurance department manages whether stable production is running or whether there are no defective products outgoing. The quality assurance department joins the project from the design verification stage, enabling intrinsic quality assurance.

See Permanently Germ-Free Touch Screen Monitors below. Impact Display Solutions specializes in developing customized display solutions to our clients’ exact specifications. Our design and engineering teams have the technical skill and experience to bring your LCD display plans to fruition. No matter what LCD panel types you need (customized or

Impact Display Solutions is a distributor of over 20 lines of touch screen manufacturers. Whether you need standard resistive and capacitive touch screens or have specialized requirements, we have your solution. Talk to our team about your specific application, such as use with gloves, rugged environments, clean rooms and more. Because we have the latest touch technologies including IR, SAW, and multi touch solutions, we are your one-stop-shop for the LCD touch screen monitor products you need. Don’t miss out on the new products based on latest technological advances in this field. Examples of unconventional options include:

PIT technology is a patented multi-touch technology. Based on the traditional infrared touch technology and the theory of total internal reflection (TIR), placing the infrared emission diode and reception diode on the lower surface of glass, the infrared beams generated by emission diodes are reflected through a prism light-guide specially designed and transmit across the front glass surface. Compared to traditional infrared touch technology, PIT touch screen has slimmer bezel, lower elevated height, and better multi-touch experience. Impact Display Solutions PIT touch screens have Win8 certification. PIT touch screens support multi-touch capability, allowing more people to touch the screen simultaneously. That allows users to have a better interactive experience. Compared to traditional infrared touch screen, 0.5mm ultralow elevated height enables PIT touch screen recognize human touch very accurately. Ultra-narrow bezel allows near-true flat appearance (as the touch transducers are placed under the screen). Protection performance enhancements are optional: waterproof or vandal-resistant.

With 4 mm and sometimes up to 6mm protection cover glass, rated IK09 which means they are protected against 10 joules impact (equivalent to impact of 5kg mass dropped from 200 mm above impacted surface). The IK rating scale identifies the ability of an enclosure to resist impact energy levels measured in joules.

As we all know, the biggest advantage of projected capacitive touch screens over other touch screen technologies is in the ease of implementation of feather-touch & multi-touch for gestures, but feather-style touching can lead to unintended activations in conventional projected capacitive touch screens. Adding force sensing overcomes that weakness of PCAPs. Force Sensing Touch Screens implement unintended touch rejection by ‘brushing off’ past accidents and it takes into account finger repositioning before selection. Force-sensing touch screen also enables new hand moves and menu-bringing features you can add to your product to enhance user experience.

Based on proven SAW touch technology, Impact Display Solutions has the capability of offering curved SAW touch screens in sizes of 21.5”, 27”, 32”, 35”, 42”. Furthermore, curved SAW touchscreens inherit and enjoy the benefits of SAW technology such as high reliability, protracted durability, sharp image clarity and vandal proofing. It’s the ideal touch solution for gaming and interactive kiosks.

So many applications demand a bright, vibrant, highly visible display in sun lit conditions. We address the need for bright displays through variety of innovative methods to enhance color, contrast, and brightness to maximize the clarity and impact of your message in very bright conditions. Don’t miss out on the new products based on latest technological advances in this area. Examples of unconventional options include:

Impact Display Solutions has extensive experience supporting projects in some of the harshest environments. Whether you are dealing with extreme temperatures, wet, oily or dirty conditions we have LCD panel types that will work for you.  We can create shock, vibration and impact resistant solutions. We are experienced with Mil Spec standards and can meet your engineering specifications. Don’t miss out on the new products based on latest technological advances in this field. Examples of cover options include (stronger glass substrates in order of toughness):

Optical bonding can increase the brightness and contrast of a display. Typically, there are air gaps between the layers of the completed LCD assembly including the substrate, cover glass and touch screen. Optical bonding can be employed to strengthen the assembly and in most cases, to improve the overall brightness, contrast ratio and readability by mitigating the light reflection between the layers. We offer variety of bonding solutions to meet your LCD touch screen monitor requirements. Don’t miss out on the new products based on latest technological advances in this field. Examples of options include:

When you need to increase readability (especially in direct sunlight) by eliminating air gap between LCD and touch screen or protective lens, or both, Impact effectively achieves that goal with optical clear adhesive (OCA) lamination process. Dry bonding with OCA is an inexpensive bonding method with a reliable track record.

Performed in the U.S., Impact uses UV-curing process for optical bonding that involves no heat with a unique patented non-optical silicone OCR bonding material (urethane acrylate) to be brought into a gel state in a Class 100 environment. Wet bonding ensures superior quality over infrared/IR curing technique and solves any delamination concerns for customers compared to dry-bonding. The following options are available:

12-15 ohms ITO-Glass EMI Shielding (12-15 ohms per sq indium tin oxide =ITO coated glass, 89% light transmission, 1.1 mm plain float glass, anti-reflective options, max size 550x850 mm)

Performed in the U.S., Impact uses IR-curing process for optical bonding that involves infrared heat to bring optical silicone OCR material to gel state. Used to optically-bond touch screens of your choice or variety of lenses similar to options for UV curing listed above but excluding Micromesh option.

To optimize image quality in all situations, we can complete an analysis of your specifications and project environment and, if needed, provide AR/AG solutions. Don’t miss out on the new products based on latest technological advances in this field. Examples of options include:

Its brasion resistance rating: the coating shall be subjected to a 20 rub eraser abrasion resistance test and meet the requirements referenced in paragraph 4.5.10 of MIL-C-675C for sleeking at the area of abrasion.

For use with your own computer, media player, or video source, Impact can deliver completed closed frame monitor designs, or simply open frame display panels of virtually any size specialized for medical, gaming, military, industrial automation and more. Unique customizations are available upon request. Don’t miss out on the new products based on latest technological advances in this field. Examples of options include:

For example, our 21.5” IP55/65-rated dust-proof & water-proof product with VGA & DVI inputs makes the monitor suitable for cleaning in medical environment

Because Impact specializes in LCDs, touch screens, computer motherboards, and value-added enhancements & assemblies, we are able to put all those products into convenient “all-in-ones” / AIOs, which include enclosures with either desktop mounts or backside VESA mounts. Click HERE for list of standard models of 15.6” to 21.5” diagonal, which consist of HD LCD, PCAP touch screen, internal computer motherboard, memory, and other components that encompass full computer functionality with convenient use interface. Please contact us to modify a standard model or make a custom-made AIO product from ground up.

Many environments, such as aircraft and the medical industry are susceptible to the effects of electro-magnetic interference. We engineer a variety of solutions for EMI mitigation, to help reduce this type of interference. Don’t miss out on the new products based on latest technological advances in this field. Examples of options include:

While many standard displays are rated for -30C already, both displays and computer motherboards can be operational all the way at -40C with optional heaters. Heaters may be controlled via manual adjustment or automatically when paired with thermistors.

10.1inch lanscape screen, wide temperature -30~+80 , 1000nits, high brightness, sunlight readable, USB touch panel, I2C touch screen, HDMI board, 10.1 inch LCD display, 10.1"" display, 1280x800, 40pin, LVDS interface, Free/All/Wide viewing ang

10.1inch lanscape screen, wide temperature -30~+80 , 1000nits, high brightness, sunlight readable, USB touch panel, I2C touch screen, HDMI board, 10.1 inch LCD display, 10.1"" display, 1280x800, 40pin, LVDS interface, Free/All/Wide viewing ang

Stockwell Elastomerics is a leading provider of gaskets for touch screens, displays and integrated touch panel assemblies that serve several functions: sealing, load distributing, gap filling, mechanical shock protection and over-press cushioning.

The obvious location is to seal the enclosure at the edge of the viewing area of the enclosure. The sealing function can be for simple dust sealing, light water exposure such as occasional water drips or cleaning or even more aggressive outdoor applications where there is heavy water exposure.

Often a touch screen gasket or display gasket will help spread the compression load of the housing or bezel on the display. Without a gasket, the enclosure that holds the display in place can create pressure points on the display. In some cases, these pressures can cause distortions, false contacts or short circuits.

Similar to load distributing, touch panel gaskets are used to fill gaps between the screen and the display and/or the screen and bezel. The display gasket will take up gaps generated by tolerance stack-ups in the device.

Display gaskets offer some degree of cushioning to protect the display from damage due to mechanical shock. In the event that a device is dropped or banged, the gasket will act as a touchscreen cushion, offering a limited amount of protection.

Touchscreen gaskets also serve as display cushions when a user presses on the display too hard. The gasket deflects, takes up and spreads the load offering some protection from over-press or overloading in a small area.

LCD dust seals and touch screen dust seals are the most basic requirement of display gasketing. These are often static (not portable), indoor applications where the device is not to be exposed to water. Sealing can be achieved by closed cell sponge materials or fine pore open cell materials such as PORON urethane foam.

Portable electronics or touchscreens used by the public such as gaming touchscreens or indoor information kiosks inevitably will be exposed to some water. This can come from cleaning and beverage splashing, or for portable devices – rain. These electronic devices are also more likely to be exposed to mechanical shocks, such as banging or dropping. Closed cell or compressed microcellular foam materials will offer more protection against incidental, light water exposure.

Outdoor displays such as outdoor information kiosks, ATMs and remote monitoring equipment require more design consideration. To contend with environments such as direct or wind-driven rain, sealing an enclosure, case or housing from ingress requires the proper material as well as proper compression on the gasket. Silicone foam or silicone sponge materials are preferred. Silicone gaskets remain flexible at low temperatures allowing for continued sealing against melting ice and snow as well as protecting against mechanical shock where many other materials will firm up in the cold and transfer energy. Other key features are: closed cell structure, low-stress relaxation, UV and ozone resistance, and general long life.

Ruggedized electronics typically need to withstand much more aggressive environments. This may include passing rain or wash down tests such as IP65, IP66 and possibly IP67. Beyond sealing, they often need to survive the cold soak drop test, tumbling, EMI susceptibility, and a variety of other tests depending on usage. View more information on ruggedizing electronics.

Light leaking is sometimes a concern with certain LCD or LED display applications. This can be addressed with black gasketing with either a very thin adhesive or a black supported adhesive. A common material configuration for this is soft PORON urethane foam with 3M 9795B adhesive. The 3M 9795B is a film supported double coat adhesive with a black PET support layer that does not pipe light.

Touchscreen gaskets and display gaskets tend to have narrow walls that don’t always lend themselves to easy installation. This can be addressed in a few ways such as fixturing or utilizing the centers as temporary supports. The preferred adhesives for touchscreen gaskets and display gaskets are repositionable adhesives such as Adchem 8311M or 3M 9415 depending on the bond strength required. Stockwell Elastomerics also offers medium and high bond strength adhesives for permanent bonding. View the current listing of pressure sensitive adhesive options.

Most touch panel or touch screen manufacturers offer guidelines for gasketing. These typically show the active screen area, viewing area, and the gasket area. The manufacturer offers various recommendations on adhesive strength and gasket material type, but caution should be taken since each application will vary.

Broad recommendations such as “closed cell foam” do not take into consideration factors such as stress relaxation, compression set, long term sealing performance, outgassing, plasticizer interaction, cost, and manufacturability. Over-designing the gasket can drive the cost up, whereas under designing could result in damaged devices and leaks when the units are in the field. Stockwell Elastomerics can offer guidance on design and manufacturability of touchscreen gaskets or touch panel gaskets. Key design points include:

The interior opening of the gasket should follow the touch screen manufacturer’s recommendation that stays clear of the active area. The outer dimension are defined by the available space behind the bezel or in the case. A rough rule of thumb is that the gasket wall should be 1.5x the thickness. (Example: .062″ thick gasket should have a gasket with .093″ or greater flange width.) This allows for die cutting and makes for a stable gasket when installed. A gasket that is taller than it is wide tends to fold over during compression. The exception to this is when the gasket is captive in a groove.

It is important to keep in mind the clamping loads. While wider gasket walls generally seal better, the overall surface area is directly related to the loads applied to the LCD and touchscreen. Compression Force Deflection curves of various materials are available to aid designers.

Some housing designs allow the touch panel gasket to wrap around the sides to make a tighter fit in the housing. Wrapping the gasket also gives the touch panel assembly additional cushioning for mechanical shock.

Proper compression of the gasket is critical to sealing. A rigid bezel or frame is required to prevent bowing between fasteners. Softer materials can help offset this however there are some limitations. Closed cell gasket materials help prevent wicking through the material but may not be soft enough. Soft open cell materials can be used but require more than 50% deflection (.062″ thick deflected to .031″ thick) in order to close the cell openings.

The gasket thickness will depend on the designed gap in the enclosure, the fastening scheme, rigidity of the housing and the level of sealing required. Many touch screen gaskets are thin and soft but as the display gets larger the tolerance stacks typically get larger as well. This may require a thicker gasket depending on the fastener locations.

PORON microcellular urethane foams are designed for electronic applications, therefore there are many standards, off-the-shelf thickness and firmness options available. Further, PORON is cast to an accurate thickness tolerance. PORON in thickness of .062″ and greater is cast to ± 10%. This is a very tight tolerance for a cellular gasketing material.

Designing the touch panel gasket for manufacturability can keep costs down – both part cost and touch panel assembling cost. For mid- and high-volume quantities, die cutting is the preferred method. A steel rule die can be produced quickly and inexpensively to allow the gasket to be kiss-cut against the adhesive release liner. Kiss-cutting allows the gasket installer to peel the gasket from a roll. Kiss-cut parts drastically improve throughput during assembly as compared to individually removing a liner from a loose part.

Some OEMs and contract manufacturers prefer to have the center of the gasket remain in place, held in place with small, breakaway tabs. Leaving the centers intact allows for easier positioning on the display when a fixture is not being used. Low tack, clean peeling adhesive is needed.

Specification requirements help with material selection, for example, NEMA 4, IP 65 or IP 66 will require closed cell or solid materials in order to pass testing. Less aggressive requirements such as NEMA 12 and IP 54 allow for more material options.

Typical UL specifications are UL 94, UL 508 (UL 60947) and UL 50. UL 94 addresses a flame requirement, UL 508 (UL 60947) is suitability for industrial controls, and UL 50 and UL 50E are for gasketing. Other UL specifications may apply depending on how and where the end product is being used.

The monitor is used to monitor, display, check, store, alarm and transmit many physiological parameters, including ECG (3/5/12 lead, arrhythmia analysis, ST segment analysis and HR ), RESP, SpO2,PR, NIBP, TEMP and IBP, etc. It is applicable for use by adult, children and neonate.

The monitor can be used in medical institutions or during transport monitoring inside/outside the hospital environment, it is used by clinical professionals or under their guidance or professionals via training, it is not suitable for use in family.

In this Arduino touch screen tutorial we will learn how to use TFT LCD Touch Screen with Arduino. You can watch the following video or read the written tutorial below.

For this tutorial I composed three examples. The first example is distance measurement using ultrasonic sensor. The output from the sensor, or the distance is printed on the screen and using the touch screen we can select the units, either centimeters or inches.

The next example is controlling an RGB LED using these three RGB sliders. For example if we start to slide the blue slider, the LED will light up in blue and increase the light as we would go to the maximum value. So the sliders can move from 0 to 255 and with their combination we can set any color to the RGB LED,  but just keep in mind that the LED cannot represent the colors that much accurate.

The third example is a game. Actually it’s a replica of the popular Flappy Bird game for smartphones. We can play the game using the push button or even using the touch screen itself.

As an example I am using a 3.2” TFT Touch Screen in a combination with a TFT LCD Arduino Mega Shield. We need a shield because the TFT Touch screen works at 3.3V and the Arduino Mega outputs are 5 V. For the first example I have the HC-SR04 ultrasonic sensor, then for the second example an RGB LED with three resistors and a push button for the game example. Also I had to make a custom made pin header like this, by soldering pin headers and bend on of them so I could insert them in between the Arduino Board and the TFT Shield.

Here’s the circuit schematic. We will use the GND pin, the digital pins from 8 to 13, as well as the pin number 14. As the 5V pins are already used by the TFT Screen I will use the pin number 13 as VCC, by setting it right away high in the setup section of code.

As the code is a bit longer and for better understanding I will post the source code of the program in sections with description for each section. And at the end of this article I will post the complete source code.

I will use the UTFT and URTouch libraries made by Henning Karlsen. Here I would like to say thanks to him for the incredible work he has done. The libraries enable really easy use of the TFT Screens, and they work with many different TFT screens sizes, shields and controllers. You can download these libraries from his website, RinkyDinkElectronics.com and also find a lot of demo examples and detailed documentation of how to use them.

After we include the libraries we need to create UTFT and URTouch objects. The parameters of these objects depends on the model of the TFT Screen and Shield and these details can be also found in the documentation of the libraries.

Next we need to define the fonts that are coming with the libraries and also define some variables needed for the program. In the setup section we need to initiate the screen and the touch, define the pin modes for the connected sensor, the led and the button, and initially call the drawHomeSreen() custom function, which will draw the home screen of the program.

So now I will explain how we can make the home screen of the program. With the setBackColor() function we need to set the background color of the text, black one in our case. Then we need to set the color to white, set the big font and using the print() function, we will print the string “Arduino TFT Tutorial” at the center of the screen and 10 pixels  down the Y – Axis of the screen. Next we will set the color to red and draw the red line below the text. After that we need to set the color back to white, and print the two other strings, “by HowToMechatronics.com” using the small font and “Select Example” using the big font.

Next is the distance sensor button. First we need to set the color and then using the fillRoundRect() function we will draw the rounded rectangle. Then we will set the color back to white and using the drawRoundRect() function we will draw another rounded rectangle on top of the previous one, but this one will be without a fill so the overall appearance of the button looks like it has a frame. On top of the button we will print the text using the big font and the same background color as the fill of the button. The same procedure goes for the two other buttons.

Now we need to make the buttons functional so that when we press them they would send us to the appropriate example. In the setup section we set the character ‘0’ to the currentPage variable, which will indicate that we are at the home screen. So if that’s true, and if we press on the screen this if statement would become true and using these lines here we will get the X and Y coordinates where the screen has been pressed. If that’s the area that covers the first button we will call the drawDistanceSensor() custom function which will activate the distance sensor example. Also we will set the character ‘1’ to the variable currentPage which will indicate that we are at the first example. The drawFrame() custom function is used for highlighting the button when it’s pressed. The same procedure goes for the two other buttons.

drawDistanceSensor(); // It is called only once, because in the next iteration of the loop, this above if statement will be false so this funtion won"t be called. This function will draw the graphics of the first example.

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor

So the drawDistanceSensor() custom function needs to be called only once when the button is pressed in order to draw all the graphics of this example in similar way as we described for the home screen. However, the getDistance() custom function needs to be called repeatedly in order to print the latest results of the distance measured by the sensor.

Here’s that function which uses the ultrasonic sensor to calculate the distance and print the values with SevenSegNum font in green color, either in centimeters or inches. If you need more details how the ultrasonic sensor works you can check my particular tutorialfor that. Back in the loop section we can see what happens when we press the select unit buttons as well as the back button.

Ok next is the RGB LED Control example. If we press the second button, the drawLedControl() custom function will be called only once for drawing the graphic of that example and the setLedColor() custom function will be repeatedly called. In this function we use the touch screen to set the values of the 3 sliders from 0 to 255. With the if statements we confine the area of each slider and get the X value of the slider. So the values of the X coordinate of each slider are from 38 to 310 pixels and we need to map these values into values from 0 to 255 which will be used as a PWM signal for lighting up the LED. If you need more details how the RGB LED works you can check my particular tutorialfor that. The rest of the code in this custom function is for drawing the sliders. Back in the loop section we only have the back button which also turns off the LED when pressed.

In order the code to work and compile you will have to include an addition “.c” file in the same directory with the Arduino sketch. This file is for the third game example and it’s a bitmap of the bird. For more details how this part of the code work  you can check my particular tutorial. Here you can download that file:

drawDistanceSensor(); // It is called only once, because in the next iteration of the loop, this above if statement will be false so this funtion won"t be called. This function will draw the graphics of the first example.

getDistance(); // Gets distance from the sensor and this function is repeatedly called while we are at the first example in order to print the lasest results from the distance sensor

Touch panel technologies are a key theme in current digital devices, including smartphones, slate devices like the iPad, the screens on the backs of digital cameras, the Nintendo DS, and Windows 7 devices. The term touch panel encompasses various technologies for sensing the touch of a finger or stylus. In this session, we"ll look at basic touch panel sensing methods and introduce the characteristics and optimal applications of each.

Note: Below is the translation from the Japanese of the ITmedia article "How Can a Screen Sense Touch? A Basic Understanding of Touch Panels"published September 27, 2010. Copyright 2011 ITmedia Inc. All Rights Reserved.

A touch panel is a piece of equipment that lets users interact with a computer by touching the screen directly. Incorporating features into the monitor like sensors that detect touch actions makes it possible to issue instructions to a computer by having it sense the position of a finger or stylus. Essentially, it becomes a device fusing the two functions of display and input.

It"s perhaps not something we think of often, but touch panels have integrated themselves into every aspect of our lives. People who enjoy using digital devices like smartphones interact with touch panels all the time in everyday life—but so do others, at devices like bank ATMs, ticket vending machines in railway stations, electronic kiosks inside convenience stores, digital photo printers at mass merchandisers, library information terminals, photocopiers, and car navigation systems.

A major factor driving the spread of touch panels is the benefits they offer in the way of intuitive operation. Since they can be used for input through direct contact with icons and buttons, they"re easy to understand and easily used, even by people unaccustomed to using computers. Touch panels also contribute to miniaturization and simplification of devices by combining display and input into a single piece of equipment. Since touch panel buttons are software, not hardware, their interfaces are easily changed through software.

While a touch panel requires a wide range of characteristics, including display visibility above all, along with precision in position sensing, rapid response to input, durability, and installation costs, their characteristics differ greatly depending on the methods used to sense touch input. Some typical touch-panel sensing methods are discussed below.

As of 2010, resistive film represented the most widely used sensing method in the touch panel market. Touch panels based on this method are called pressure-sensitive or analog-resistive film touch panels. In addition to standalone LCD monitors, this technology is used in a wide range of small to mid-sized devices, including smartphones, mobile phones, PDAs, car navigation systems, and the Nintendo DS.

With this method, the position on screen contacted by a finger, stylus, or other object is detected using changes in pressure. The monitor features a simple internal structure: a glass screen and a film screen separated by a narrow gap, each with a transparent electrode film (electrode layer) attached. Pressing the surface of the screen presses the electrodes in the film and the glass to come into contact, resulting in the flow of electrical current. The point of contact is identified by detecting this change in voltage.

The advantages of this system include the low-cost manufacture, thanks to its simple structure. The system also uses less electricity than other methods, and the resulting configurations are strongly resistant to dust and water since the surface is covered in film. Since input involves pressure applied to the film, it can be used for input not just with bare fingers, but even when wearing gloves or using a stylus. These screens can also be used to input handwritten text.

Drawbacks include lower light transmittance (reduced display quality) due to the film and two electrode layers; relatively lower durability and shock resistance; and reduced precision of detection with larger screen sizes. (Precision can be maintained in other ways—for example, splitting the screen into multiple areas for detection.)

Capacitive touch panels represent the second most widely used sensing method after resistive film touch panels. Corresponding to the terms used for the above analog resistive touch panels, these also are called analog capacitive touch panels. Aside from standalone LCD monitors, these are often used in the same devices with resistive film touch panels, such as smartphones and mobile phones.

With this method, the point at which the touch occurs is identified using sensors to sense minor changes in electrical current generated by contact with a finger or changes in electrostatic capacity (load). Since the sensors react to the static electrical capacity of the human body when a finger approaches the screen, they also can be operated in a manner similar to moving a pointer within an area touched on screen.

Two types of touch panels use this method: surface capacitive touch panels and projective capacitive touch panels. The internal structures differ between the two types.

Surface capacitive touch panels are often used in relatively large panels. Inside these panels, a transparent electrode film (electrode layer) is placed atop a glass substrate, covered by a protective cover. Electric voltage is applied to electrodes positioned in the four corners of the glass substrate, generating a uniform low-voltage electrical field across the entire panel. The coordinates of the position at which the finger touches the screen are identified by measuring the resulting changes in electrostatic capacity at the four corners of the panel.

While this type of capacitive touch panel has a simpler structure than a projected capacitive touch panel and for this reason offers lower cost, it is structurally difficult to detect contact at two or more points at the same time (multi-touch).

Projected capacitive touch panels are often used for smaller screen sizes than surface capacitive touch panels. They"ve attracted significant attention in mobile devices. The iPhone, iPod Touch, and iPad use this method to achieve high-precision multi-touch functionality and high response speed.

The internal structure of these touch panels consists of a substrate incorporating an IC chip for processing computations, over which is a layer of numerous transparent electrodes is positioned in specific patterns. The surface is covered with an insulating glass or plastic cover. When a finger approaches the surface, electrostatic capacity among multiple electrodes changes simultaneously, and the position were contact occurs can be identified precisely by measuring the ratios between these electrical currents.

A unique characteristic of a projected capacitive touch panel is the fact that the large number of electrodes enables accurate detection of contact at multiple points (multi-touch). However, the projected capacitive touch panels featuring indium-tin-oxide (ITO) found in smartphones and similar devices are poorly suited for use in large screens, since increased screen size results in increased resistance (i.e., slower transmission of electrical current), increasing the amount of error and noise in detecting the points touched.

Larger touch panels use center-wire projected capacitive touch panels in which very thin electrical wires are laid out in a grid as a transparent electrode layer. While lower resistance makes center-wire projected capacitive touch panels highly sensitive, they are less suited to mass production than ITO etching.

Above, we"ve summarized the differences between the two types of capacitive touch panels. The overall characteristics of such panels include the fact that unlike resistive film touch panels, they do not respond to touch by clothing or standard styli. They feature strong resistance to dust and water drops and high durability and scratch resistance. In addition, their light transmittance is higher, as compared to resistive film touch panels.

On the other hand, these touch panels require either a finger or a special stylus. They cannot be operated while wearing gloves, and they are susceptible to the effects of nearby metal structures.

Surface acoustic wave (SAW) touch panels were developed mainly to address the drawbacks of low light transmittance in resistive film touch panels—that is, to achieve bright touch panels with high levels of visibility. These are also called surface wave or acoustic wave touch panels. Aside from standalone LCD monitors, these are widely used in public spaces, in devices like point-of-sale terminals, ATMs, and electronic kiosks.

These panels detect the screen position where contact occurs with a finger or other object using the attenuation in ultrasound elastic waves on the surface. The internal structure of these panels is designed so that multiple piezoelectric transducers arranged in the corners of a glass substrate transmit ultrasound surface elastic waves as vibrations in the panel surface, which are received by transducers installed opposite the transmitting ones. When the screen is touched, ultrasound waves are absorbed and attenuated by the finger or other object. The location is identified by detecting these changes. Naturally, the user does not feel these vibrations when touching the screen. These panels offer high ease of use.

The strengths of this type of touch panel include high light transmittance and superior visibility, since the structure requires no film or transparent electrodes on the screen. Additionally, the surface glass provides better durability and scratch resistance than a capacitive touch panel. Another advantage is that even if the surface does somehow become scratched, the panel remains sensitive to touch. (On a capacitive touch panel, surface scratches can sometimes interrupt signals.) Structurally, this type of panel ensures high stability and long service life, free of changes over time or deviations in position.

Weak points include compatibility with only fingers and soft objects (such as gloves) that absorb ultrasound surface elastic waves. These panels require special-purpose styluses and may react to substances like water drops or small insects on the panel.

All in all, however, these touch panels offer relatively few drawbacks. Recent developments such as improvements in manufacturing technology are also improving their cost-performance.

The category of optical touch panels includes multiple sensing methods. The number of products employing infrared optical imaging touch panels based on infrared image sensors to sense position through triangulation has grown in recent years, chiefly among larger panels.

A touch panel in this category features one infrared LED each at the left and right ends of the top of the panel, along with an image sensor (camera). Retroreflective tape that reflects incident light along the axis of incidence is affixed along the remaining left, right, and bottom sides. When a finger or other object touches the screen, the image sensor captures the shadows formed when the infrared light is blocked. The coordinates of the location of contact are derived by triangulation.

While this type differs somewhat from the above touch panels, let"s touch on the subject of electromagnetic induction touch panels. This method is used in devices like LCD graphics tablets, tablet PCs, and purikura photo sticker booths.

This input method for graphics tablets, which originally did not feature monitors, achieves high-precision touch panels by combining a sensor with the LCD panel. When the user touches the screen with a special-purpose stylus that generates a magnetic field, sensors on the panel receive the electromagnetic energy and use it to sense the position of the pen.

Since a special-purpose stylus is used for input, input using a finger or a general-purpose stylus is not possible, and the method has limited applications. Still, this has both good and bad points. It eliminates input errors due to the surrounding environment or unintended screen manipulation. Since the technology was intended for use in graphics tablets, it offers superior sensor precision—making it possible, for example, to change line width smoothly by precisely sensing the pressure with which the stylus is pressed against the screen (electrostatic capacity). This design approach also gives the screen high light transmittance and durability.

The table below summarizes the characteristics of the touch panels we"ve looked at. Keep in mind that even in devices based on the same sensing method, performance and functions can vary widely in the actual products. Use this information only as an introduction to general product characteristics. Additionally, given daily advances in touch-panel technological innovations and cost reductions, the information below is only a snapshot of current trends as of September 2010.

Each touch-panel type offers its own strengths and weaknesses. No single sensing method currently offers overwhelming superiority in all aspects. Choose a product after considering the intended use and environmental factors.

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