thermal management of lcd displays quotation

LCD displays are commonly used today in devices that require information to be displayed in human-perceptible form. LCD displays are typically comprised of an enclosure, a LCD module, backlights and supporting electronics. Since LCD displays use thin depth LCD modules to display information as opposed to larger in depth cathode ray tube (CRT) displays for similar sized screens, LCD displays are often used in devices that have packaging and/or space constraints. Unlike LCD displays, the tube in a CRT display increases substantially in depth as the screen size increases.

Electronic devices, such as fuel dispensers and automatic teller machines (ATM) for example, use displays to display information to users of these devices. Such information may be instructions on how to use the machine or a customer"s account status. Such information may also include other useful information and/or services that generate additional revenue beyond the particular function of the device, such as advertising or newsworthy information. Through increasingly easier and cheaper access to the Internet, it has become even more desirable for electronic devices to use displays that are larger in screen size and employ higher resolution color graphics without substantially increasing the depth of the display due to packaging limitations. Therefore, LCD displays are advantageous to use in displays in electronic devices because of the thin nature of LCD modules.

LCD displays used in outdoor devices typically use an environmentally-sealed enclosure since LCD displays include internal components, such as electronics, backlights and display modules, whose operations are sensitive to outdoor conditions, such as water and dust. However, the backlights and the electronic circuitry generate extreme heat during their operation thereby raising the ambient air temperature inside the enclosure. The ambient temperature in the enclosure rises even more in outdoor devices due to sunlight heat. If the ambient temperature in the enclosure is not managed, components of the LCD display 10 may fail. For example, the LCD module may start to white or black out if the ambient temperature inside the enclosure rises above a certain temperature.

One method keeping the ambient air temperature lower inside the enclosure is to provide a larger enclosure so that it takes more heat generated by the internal components of the LCD display and external sources, such as the sunlight, to raise the ambient air temperature inside the enclosure. However, increasing the size of the enclosure is counter to the goal of using a thin depth enclosure for a LCD display.

Therefore, a need exists to provide a thin LCD display enclosure that is sealed from the environment and is capable of efficiently dissipating heat generated by the internal components of the LCD display and external heat, such as sunlight.

The present invention relates to a thermal management system for a liquid crystal display (LCD) that is placed inside a thin depth enclosure and may be incorporated into an outdoor device. The thermal management system efficiently transfers and dissipates heat in the ambient air of the LCD display enclosure generated by components of the LCD display and external heat, such as sunlight.

In one embodiment of the present invention, the LCD display comprises an environmentally-sealed, heat conducting enclosure with a backlight assembly having at least one backlight. The backlight assembly is connected to the inside rear portion of the enclosure. A heat sink is attached on the outside rear portion of the enclosure. Heat generated by the backlights is transferred using natural convection from the enclosure to the heat sink, and the heat sink dissipates such heat to the atmosphere.

In another embodiment of the present invention, the LCD display contains the backlight assembly as discussed in the preceding paragraph. The LCD display also contains a lens on the front portion of the enclosure and a LCD module between the lens and the backlight assembly. The LCD module is placed in between the top and bottom of the enclosure to provide air gaps inside and at the top and the bottom of the LCD module to form a circular airflow path around the LCD module. A fan is placed in the airflow path to forcibly move heated air inside the enclosure from the front of the LCD module to the rear portion of the enclosure for heat dissipation through the heat sink and to the atmosphere.

The LCD display may be placed in any type of electronic device, including but not limited to a kiosk, a fuel dispenser, a personal computer, an elevator display, and an automated teller machine (ATM). The LCD display may display information and other instructions to a user of an electronic device incorporating the LCD display. If the LCD display has a touch screen, the LCD display may also act as an input device.

FIG. 1 is a schematic diagram of one embodiment of a thin depth LCD display enclosure having a thermal management system according to the present invention;

The present invention relates to a thermal management system for a LCD display having a thin depth enclosure, and that may be placed in and outdoor environment and/or device. A thermal management system aids the LCD display 10 in overcoming the effects of internal heat generated by components of the LCD display 10 and heat from sunlight heat, if the LCD display 10 is placed in sunlight. The thermal management system also allows a thinner depth enclosure to be used for the LCD display. Use of a thin depth LCD display may be useful for addressing space and packaging issues for devices requiring a display.

A LCD display 10 according to one embodiment of the present invention is illustrated in FIG. 1. The LCD display 10 comprises an environmentally-sealed enclosure 12 that has a front portion 14 and a rear portion 16. The environmentally-sealed enclosure 12 protects the internal components of the LCD display 10 from external elements that may affect the proper operation, such as water, dust, etc. The enclosure 12 is constructed out of a heat conducting material, such as sheet metal, aluminum, or copper for example, so that heat generated by components of the LCD display 10 can be dissipated outside of the enclosure 12 to the atmosphere using convective heat transfer. In one embodiment, the depth of the enclosure 12 is approximately 40 millimeters.

The enclosure 12 includes a transparent lens 18 at the front portion 14 of the enclosure 12 for external viewing of the LCD display 10. The lens protects the internal components of the LCD display 10 and also allows the LCD module 26 to be viewed from outside of the enclosure 12. The lens 18 may be constructed out of clear plastic, glass, Plexiglas, or other transparent material so long as the LCD module 26 can be viewed from outside the enclosure 12. The LCD module 26 may be an active or passive matrix display, may include color, and may pass or block light to provide information for external viewing.

A backlight assembly 20 is provided in the rear portion 16 of the enclosure 12. The backlight assembly 20 holds one or more backlights 22. The backlights 22 project light towards the rear of the LCD module 26 so that the LCD module 26 can be properly viewed through the lens 18. In this particular embodiment, the backlights 22 are flourescent light bulbs. When power is provided to the backlights 22, light is projected from the backlights 22 towards the LCD module 26. The LCD module 26, depending on its design, either blocks the light or allows the light to pass through to display information for external viewing in human-perceptible form through the lens 18.

The LCD display 10 also includes a thermal management system for convectively moving and dissipating heat generated by internal components of the LCD display 10, such as the backlights 22 and electronic circuitry (not shown) in the enclosure 12, as well as external heat on the enclosure 12, such as sunlight. Heat generated by these sources raises the ambient air temperature inside the enclosure 12 thereby possibly causing the LCD display 10 to not function properly. Although the backlights 22 are designed to operate at higher temperatures, the heat generated by the backlights may affect the performance of the LCD module 26. For example, if the LCD module 26 is a color module, the color will start to fade as the ambient temperature inside the enclosure 12 increases beyond designed operating temperatures of the LCD module 26.

It may be desirable for a LCD display 10 in an outdoor device to be brighter than would otherwise be required in an indoor device due to light and glare created by sunlight. Increasing the brightness of the backlights 22 causes the backlights 22 to generate more heat and/or the power to the electronic circuitry to be greater. Because the enclosure 12 is environmentally-sealed, heat generated by the backlights 22, the electronic circuitry, and external sources needs to be dissipated outside of the enclosure 12 in order for the LCD module 26 to operate at a lower temperature. For example, some LCD modules 12 may need to be kept at temperatures at or lower than 70 degrees Celsius to operate properly. One solution is to reduce the power to the backlights 22 that in turn lowers the heat generated by the backlights 22, but this also reduces the brightness of the LCD display 10.

The present invention may be used to avoid having to reduce the brightness of the backlights 22. Heat generated by the LCD display 10 may be convectively dissipated in two manners. The LCD display 10 dissipates heat inside the enclosure 12 using one or more heat sinks 24 attached to the rear portion 16 of the enclosure 12. The heat sink 24 may contain one or more fins 25 to create greater surface area on the heat sink 24 for dissipation of heat. This heat sink 24 ensures that the internal surface temperature of the enclosure 12 is kept as close to the atmospheric temperature as possible to ensure that the heated air inside the enclosure 12 is absorbed by the enclosure 12. FIG. 1 illustrates the heat dissipated by the heat sink 24 to the atmosphere using arrows pointing upward on the outside of the rear portion 16 of the enclosure 12.

Heat generated by the backlights 22 is dissipated through the heat sink 24. The backlight assembly 20 is located against the surface of the rear portion 16 of the enclosure 12. In one embodiment, the center of the backlights is approximately 3.25 millimeters from the rear portion 16 of the enclosure 12. In this manner, heat generated by the backlights 22 is convectively transferred to the atmosphere, using natural convection. The heat generated by the backlights 22 is transferred to the rear portion 16 of the enclosure 12 and to the heat sink 24. The closer the heat sink 24 is to the backlights 22, the faster heat generated by the backlights 22 can be transferred outside of the enclosure 12 thereby reducing the chance of such heat to increase the ambient air inside the enclosure 12.

Heat generated by the backlights 22 that is not immediately dissipated through the rear portion 16 of the enclosure 12 and the heat sink 24 causes the ambient air temperature inside the enclosure 12 to rise. Heat generated by electronic circuitry inside the enclosure 12 and any external heat on the enclosure 12, such as sunlight, also causes the ambient air temperature inside the enclosure 12 to rise. To dissipate the heat in the ambient air, thereby cooling the LCD module 26, an airflow path 30 is created around the LCD module 26 by placement of the LCD module 26 between the lens 18 and the backlight assembly 20. In one embodiment of the present invention, the back of the LCD module 26 is placed approximately 12.9 millimeters from the backlights 22 to properly diffuse and evenly backlight the LCD module 26. The front of the LCD module 26 is placed approximately 9.4 millimeters from the lens 18 so that any protrusion on the lens 18 does not damage the LCD module 26. Spacing between the lens 18 and the LCD module 26 also allows air to be routed across the LCD module 26 for thermal management, as discussed below. The LCD module 26 is also placed between the top and bottom of the enclosure 12 in the vertical plane so that air gaps 28A and 28B are formed on the top and bottom of the LCD module 26. In this manner, air is free to flow around the LCD module 26 in a circular fashion, as illustrated by the counter-clockwise airflow arrows moving around the LCD module 26 in FIG. 1.

In order to dissipate heat in the ambient air in the enclosure 12, a fan 32 is placed in the airflow path 30. The fan 32 provides forced convection of the ambient air inside the enclosure 12 to the rear portion 16 of the enclosure 12 for dissipation. In one embodiment, the fan 32 is placed at the top of the enclosure 12 above the LCD module 26. During operation, that fan 32 rotates counter-clockwise to create the counter-clockwise circular airflow path 30. The ambient air is routed to the rear of the LCD module 26 and to the rear portion 16 of the enclosure 12 for dissipation through the enclosure 12 to the heat sink 24 and to the atmosphere.

The fan 32 may be any type of air movement device that can create the airflow path 30; however, one embodiment of present invention employs a laminar flow fan 32 manufactured by Delta Corporation. An example of such a laminar flow fan 32 is disclosed in U.S. Pat. No. 5,961,289 entitled “Cooling axial flow fan with reduced noise levels caused by swept laminar and/or asymmetrically staggered blades,” incorporated herein by reference in its entirety. A laminar flow fan 32 creates a sheet of air, rather than turbulent air, across the LCD module 26. The laminar airflow is more efficient than turbulent airflow for moving air and transferring heat from the front of the LCD module 26 to the rear portion 16 of the enclosure 12. A more efficient fan 32 allows selection of a fan 32 that is smaller in size since it may require less rotations of the fan 32 to move an amount of air desired and/or move the same amount of air in a smaller airflow path 30. Each of these factors contributes to a smaller fan 32 size that in turn contributes to a thinner depth enclosure 12. In one embodiment, the fan 32 operates at approximately 3400 revolutions per minutes (RPM). However, the present invention may use any type of fan 32, including those that generate turbulent air. The fan 32 speed may also be adjusted to move air in the desired manner and efficiency.

FIG. 2 illustrates one embodiment of a device that incorporates the LCD display 10 known as a “kiosk”34. A kiosk 34 is any type of interactive electronic device that provides an input device, an output device, or both. Kiosks 34 are typically used in retail environments to sell products and/or services to customers. Some common types of kiosk 34 include vending machines, fuel dispensers, automatic teller machines (ATM), and the like. FIG. 2 illustrates one example of a kiosk 34 that includes the LCD display 10 illustrated in FIG. 1 as an output device for displaying information. Soft keys 36 are located on each side of the LCD display 10 as an input device for customer selections; however, an input device may also take others forms, such as a keypad 38, touch screen keys on the LCD display 10 (not shown), card entry device, magnetic or optically encoded cards for example, voice recognition, etc. The LCD display 10 of the present invention is particularly suited for kiosks 34 that are located in outdoor environments where the enclosure 12 of the LCD display 10 is environmentally-sealed. However, the LCD display 10 may be placed in any type of kiosk 34 regardless of whether the kiosk 34 is placed in an outdoor environment.

FIG. 3 illustrates one embodiment of a communication architecture used for the LCD display 10. The LCD display 10 comprises a display CPU board 40 that contains electronics and software. In this particular embodiment, the display CPU board 40 contains a single display microprocessor 42 and display software 44. The display software 44 contains both volatile memory 46, such as RAM and/or flash memory, and non-volatile memory 48, such as EPROM and/or EEPROM. The display software 44 contains program instructions for the display microprocessor 42 and may also contain information to be displayed on the LCD module 26. The display microprocessor 42 may also manages information received from external sources and controls the operation of the LCD module 26.

In this embodiment, information is communicated from one or more external devices to the display microprocessor 42 to then be displayed on the LCD module 26. A main controller 50 is provided as the interface to the display microprocessor 42. The main controller 50 may be any type of control system, including a point-of-sale system for example. The main controller 50 may be coupled to more than one display microprocessor 42 for managing multiple LCD modules 26. The main controller 50 may also be connected to a local server 56, located in close proximity to the LCD display 10, that sends information to be displayed on the LCD module 26. A remote server 52, located remotely from the LCD display 10, may also be provided to send information to the LCD module 26. The remote server 52 may send information over a network 54 directly to the display microprocessor 42, through the main controller 50, and/or through the local server 56 to be eventually displayed on the LCD module 26. The remote server 52, the local server 56, the main controller 50, and the display microprocessor 42 may be coupled each other through either a wired or wireless connection or network 54 using any type of communication technology, including but not limited to the Internet, serial or parallel bus communication, radio-frequency communication, optical communication, etc.

Examples of Internet information management that may be used with the present invention to send information to a LCD display 10 and/or communicate information entered into a LCD display 10 having a touch screen or other electronic device incorporating an LCD display 10 are disclosed in U.S. Pat. Nos. 6,052,629 and 6,176,421 entitled “Internet capable browser dispenser architecture” and “Fuel dispenser architecture having server” respectively, both of which are incorporated herein by reference in their entirety.

FIG. 4 illustrates another exemplary outdoor device that may incorporate the LCD display 10 of the present invention known as a “fuel dispenser” 60. A fuel dispenser 60 may also be considered a type of kiosk 34 depending on its configuration and features. The illustrated fuel dispenser 60 contains a LCD display 10 for providing instructions and/or information to a customer at the fuel dispenser 60. The fuel dispenser 60 is comprised of a housing 62 and at least one energy-dispensing outlet, such as a hose 64 and nozzle 66 combination, to deliver fuel to a vehicle (not shown). As illustrated in FIG. 2, the fuel dispenser 60 may have other input and/or output devices for interaction with a customer, such as price-per-unit of fuel displays 72, soft-keys 36, a receipt printer 68, a radio-frequency identification (RFID) antenna 74, and a cash acceptor 70.

Also note that the LCD display 10 may also be placed external to the fuel dispenser 60 and attached to the fuel dispenser 60 as disclosed in co-pending patent application entitled “Multiple browser interface,” filed on Apr. 23, 2001.

Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. It should be understood that the present invention is not limited to any particular type of component in the LCD display 10 including, but not limited to the enclosure 12, the lens 18, the backlight 22 and backlight assembly 20, the heat sink 24, the LCD module 26, and the fan 32. Additionally, the LCD display 10 may be used in any type of device having or using a display, including but not limited to a personal computer, a kiosk 34, an elevator, an ATM, and a fuel dispenser 60. Also for the purposes of this application, couple, coupled, or coupling is defined as either a direct connection or a reactive coupling. Reactive coupling is defined as either capacitive or inductive coupling.

One of ordinary skill in the art will recognize that there are different manners in which these elements can accomplish the present invention. The present invention is intended to cover what is claimed and any equivalents. The specific embodiments used herein are to aid in the understanding of the present invention and should not be used to limit the scope of the invention in a manner narrower than the claims and their equivalents.

High end consumer-TVs use active LEDs in direct lit LCD-LED displays to enhance the viewing experience of the end customers. In direct-lit displays, 2D dimming and boosting are used to actively adapt the light from the display LEDs to the brightness distribution of the picture content, enabling the display of high dynamic range contrast video with brighter lights and darker blacks. The solder joint reliability and lifetime of the LEDs is an ongoing concern, therefore the dimming and boosting algorithms need to incorporate protective measures. In this work thermal management of active LEDs in a consumer TV LCD-LED display is discussed. Transient LED temperatures are investigated for different typical timescales and picture loads. The cycle time dependent temperature is subsequently applied to a simplified solder fatigue model (described elsewhere) incorporating the effect of short creep times, resulting in a typical solder joint damage expression as a function of boost time. This damage function is applied to a database of timescales typical for video picture loads, and different protection strategies are assessed as to their effect on the total damage over long viewing times. This enables the use of the time scale differences between the optical response of the LED, the thermal response of the LED and the resulting effect on the solder creep mechanism, to ensure an enhanced consumer viewing experience at no additional cost to the display LED solder joints lifetime.

Light-emitting diodes (LEDs), have emerged as a new light source for backlight units in novel liquid crystal displays due to their advantages in optical performance and their environmentally friendly features. The characteristics of LEDs, however, are inherently accompanied by high heat dissipation, and performance of an LED device strongly depends on the operating temperature. Therefore, proper thermal management is required to facilitate reliable operation of a backlight unit in a display…Expand

Here is a picture inside the TV without the rear cover. The power supply includes the inverter stage for the backlight panel using only two HV transformers. Such design idea sounds very good because all EEFL tubes are connected in parallel avoiding the use of small transformers/inverters stages for each lamp minimizing in this way electronic issues on the backlight stage.

Compared to former CCLF, the new EEFL shows superior performance and applications. This incredible technology combines low power consumption and enhanced luminescence as compared to similar lighting sources. The most attractive feature of EEFL (External Electrode Fluorescent Lamp) is the absence of electrodes in the discharge tube, which is the main factor limiting lamp life. Electrode burn-out is the main cause of fault in CCFL. Because each CCFL lamp need its own ballast the new EEFL technology is simpler in electronics circuitry reducing in this way the rate of failures. EEFL lamps consist of a completely enclosed glass tube with external metal electrodes at both ends. This design minimizes electrode burn-out and results in a longer lamp life. Because the electrodes in former CCFL technology are in direct contact with the rare gasses, CCFL run warmer than the EEFL which are completely cool. On average, EEFL lamps have a lamp life of over 50,000 hours.

I figured out that three main areas on the circuit layout requires additional cooling. The hottest part was the digital class D audio amplifier (STA381BW) because overheats to much (manufacturer datasheet claims approx 3 watts of heat dissipation !!!) so I put a passive aluminum cooler to cool it down. Because the rear plastic cover touched the cooler I cut one of the corners. Using a smaller one was to weak to cool down the device at safe temperatures.

The digital scaler image MT5366 processor and glue logic ICs are located below a metallic RFI shield acting at the same time as a heatsink. Unfortunately the metal shield in use affects the efficiency on thermal conductivity of heat because is to thin leading to hot spots on the components. To correct such design issue the most convenient is to install a passive cooler. To cool down the MT5366 system on chip platform processor an older 486 mother board heatsink (the black one after changes third picture below) do the job well. The use of a thicker heatsink improves the thermal conductivity (spread of heat) avoiding hot spots on the devices.

The last part that requires additional cooling was the HDMI switch inputs selector (SiI9185 device schematic picture above) soldered on the right corner next to the HDMI inputs. Its based on the HDMI 1.3, DDC, HDCP specifications including a CEC (consumer electronics control) single wire bus interface to transmit I/O remote commands through a home network and EDID display identification (plug & play feature stored on serials EEPROMs). Researching datasheets from other versions I figured out that the device in operation consumes approximately 1.5 watts average but such information is not released by manufacturer. The device reach a working temperature of approximately 100 grads Celsius when HDMI inputs are enabled receiving stream data. Watching TV channels (digital DVB or analog cable) the HDMI switch remains cool because is in power down/suspend mode. At glance the HDMI switch overheats only when the inputs are enabled. Without an appropriate heatsink the life endurance of the device is affected because such operating condition can lead to a short circuit on terminals due silicon breakdown !!! . The HDMI switch integrates electrostatic discharge protections on its inputs up to 2kV discarding any possibilities of damages due weak ESD spikes but strong lightning electromagnetic discharges are a big problem without ESD protectors.

In the case of factory cooling all mentioned devices use the "ePad" enhancement, a small metal surface below the IC core case to transfer the silicon heat to PCB board. Despite the idea to reduce manufacturing costs avoiding in this way the use of external heatsinks such cheap PCB cooling solution is not appropriate at all. We verified on all the mentioned devices an excessive heat that unfortunately can lead to operational malfunctions/issues leading to a short durability.

After changes the overall heat is reduced due the improvements on heat conductivity and air convection cooling reducing the average working temperature on overall components avoiding at the same time hot spots on digital ICs (core of the silicon device).

To improve more the cooling on the T-Con LCD panel board we put a SinoGuide TCP400 series thermal pad on the main IC to increase the heat transfer on the metallic shield (this is more thick in diameter and seems to be OK for cooling purposes).

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.

AZ Displays continues to expand its product offering for the industrial and medical market. The newest IPS module, ATM1025L1-CT, is a unique wide aspect ratio IPS display that is designed to operate at -30 to 85 C. This LCD module has already received a lot of interest in the market for medical applications, time management systems, marine clusters, and several other designs. This 10.25″ display was designed with high performance in mind, with the following specifications:

In order for the LCD module to operate at extended temperatures, AZ Displays used premium polarizers and liquid crystal fluid to initiate the active matrix into operating with minimal latency at the low temperature end (-30 C), and high tolerance to warping and burning of the polarizer at extreme heat. This quality, along with high temperature rated IC’s and an option for optical bonding between LCD and touch screen make this module highly suitable for a wide array of applications and environments.

LCDs used in outdoor situations have many concerns to deal with in addition to any that they might normally encounter during indoor use. Initially some concerns are weather related such as moisture in the air or extreme temperatures. Another concern that is often not understood or just not known about at all is sunlight damage.

Liquid crystal displays use organic components that are susceptible to UV (<400 nm) and IR (>750 nm). These bandwidths of radiation have an observable impact on the organic components in LCDs. Extended exposure has been known to cause a color shift and a washed out look to images displayed with the LCD.

Over time the UV and IR radiation degrade the organic components causing them to fail to function properly. The amount of time it takes can vary depending on brand and model as well as specific weather conditions the display has been exposed to. For instance some atmospheric disturbances can reduce the amount of Ultraviolet that is transmitted to the display.

In any case it is important to protect your display from the elements, especially if it is going to be exposed to harsh environments not intended by the manufacturer. One way to do this would be to utilize a Hot Mirror with a UV blocker. This will significantly reduce the amount of IR radiation between 750 nm and 1200 nm, as well as the UV radiation below 400 nm. If the LCD is going to be used outdoors for extended periods then an extended hot mirror may be necessary, which extends the bandwidth protection out to 1600 nm and will help reduce some of the longer wavelength IR damage.

Another concern with liquid crystal displays are their susceptibility to overheating due to excess IR radiation. The LCD is intended to operate within a certain range of temperatures according to the manufacturer’s instructions and outdoor use can lead to higher than normal temperatures. The display being exposed to excessive heat can cause the crystal to become isotropic and fail to perform properly. A hot mirror can help alleviate these concerns as well by reducing the amount of infrared radiation that heats the display.

Before we get into specifics about how this would work, it is important to understand that liquid crystal display panels and polarizers utilize organic compounds that are susceptible to high heat and light energy stress. These organic compounds will eventually break down if deployed in high stress environments. One such contributing factor to LCD panel failure is the use of a high energy unfiltered illuminator. The near IR and shorter UV wavelengths not only add excess heat that may overheat the liquid crystal and prevent them from working properly, but they also add UV band energy that is destructive to organic compounds.

Over time the UV and IR will degrade and damage the LCD panel and polarizers to the point that they produce an unacceptably poor performance. In most applications this is observed to be color shift, washed out images and an observable raise in the darkness levels produced by a damaged LCD panel.

In order to help prolong the onset of such damage a set of UV and IR band filters and mirrors can be used to minimize the amount of harmful energy that is conveyed to the LCD panel from the illuminator. In order to determine what combination of filters and mirrors are best for any particular application it is important to know how each material reacts to the various intensities of bandwidths emitted by your chosen illuminator.

Frequently the Illuminators used in LCD systems are gas discharge lamps such as xenon arc lamps and metal halide light sources. A standard hot mirror that reflects energy between 750 and 1200 nm can be used to mitigate the majority of IR energy being conveyed to the LCD panel. In addition a UV blocker can be used to mitigate the damage from energy below 400 nm.

Other thin film coatings and substrates can be utilized to reduce the IR and UV damage to an LCD panel. Any solution must be well researched to minimize concerns so that a sufficient cooling mechanism is planned and allowed for in the application.

Screen display technologies require supporting components that enable them to function or enhance performance. From screen bonding systems to vibration management, optically clear adhesive (OCA), window tape, barrier film and thermal management, LCD and/or OLED display technologies need these supporting solutions for trustworthy device operation over extended periods of time.

Boyd’s expertise in advanced rotary die cut converting with ultra-tight tolerances, superb cleanroom footprint and innovative raw material selections are critical to the high design and manufacturing designs of display module components. Our innovative approach to manufacturing and rotary die cut also pushes us to work “outside the box.” We search for opportunities that push the limits of product integration – utilizing our world class precision converting and manufacturing engineering knowledge to combine multiple unique products into one, simple deliverable, helping customers reduce supply chain and assembly complexity.

Our innovative segmented frame manufacturing technology for display lens adhesives and window tape gaskets allows Boyd to replace original full window frame designs that drive a high amount of material waste with yield-optimized assemblies that have zero gap tolerance, delivered to the assembly chain in a format optimized for automated as well as manual assembly operations. These solutions act as gaskets and cushions, help protect against dust, moisture and shock or vibration impact.

Boyd’s OLED advanced energy management and sealing solutions are optimized to treat energy in a variety of manifestations, including EMI, thermal spreading & insulation, sealing, encapsulating, vibration absorption & cushioning, barriers, in one to two cohesive deliverables.

Optically clear adhesive (OCA) is one of the most challenging materials to die-cut and handle but are critical to ultimate screen clarity, contrast and minimized reflection. Boyd’s Class 100 cleanroom precision converting environments and excellent historical OCA manufacturing quality make us the global leader in optically clear adhesive custom fabrication and die cutting.

The AKCP Programmable Sensor Display plugs into any sensorProbe+ (SP2+, SPX+) base unit and can be programmed to display the data from any AKCP Intelligent or virtual sensor. Mount a single display on the end of an aisle for data center monitoring, or warehouse monitoring. Place on the door of every cabinet, or the wall of the room. LED indicators alert if a sensor is in critical condition, as well as the on-screen display of the critical or warning status.

Chassis temperature is monitored at two points using thermistors. Unique to the SysCool is the use of lower cost 2-wire fans instead of the more expensive and harder to get 3- or 4-wire fans. The SysCool circuitry monitors absolute fan current and pulses in the current to determine fan RPM and fan health. Fan RPM is cont rolled by Pulse Width Modulating the current driving the fans. The fan speed profile is a linear ramp from 30% to 100% over a range of 25-45 deg C, not a step function as in other cont rollers. Thus speed hunting is eliminated and fan life is maximized.

The SysCool provides front panel LED notification as defined in ANSI / VITA 40-2003 for clear, unambiguous alarm state notification to the system operator. In addition, a remote alarm indicator output is provided which is capable of sinking 300mA at 5V in order to activate a relay or other external alarm device.

The all new TEC Temperature Controllers are packed with new features at a competitive price, bringing you unparalleled value from the company that does it best. These high-performance controllers are easy-to-use, feature a compact design and bright LCD display. They can also be used for pressure, flow, and humidity control.

Tempco is your ISO 9001:2015 Certified custom manufacturer of electric heating elements, temperature sensors, temperature controllers & process heating systems.

Advanced LED video wall with MicroLED models in 0.6, 0.7 and 0.9mm pixel pitches, and 1.2mm pixel pitch standard LED; with powerful processing, proprietary alignment technology and off-board electronics.

Planar® CarbonLight™ VX Series is comprised of carbon fiber-framed indoor LED video wall and floor displays with exceptional on-camera visual properties and deployment versatility, available in 1.9 and 2.6mm pixel pitch (wall) and 2.6mm (floor).

From cinema content to motion-based digital art, Planar® Luxe MicroLED Displays offer a way to enrich distinctive spaces. HDR support and superior dynamic range create vibrant, high-resolution canvases for creative expression and entertainment. Leading-edge MicroLED technology, design adaptability and the slimmest profiles ensure they seamlessly integrate with architectural elements and complement interior décor.

From cinema content to motion-based digital art, Planar® Luxe Displays offer a way to enrich distinctive spaces. These professional-grade displays provide vibrant, high-resolution canvases for creative expression and entertainment. Leading-edge technology, design adaptability and the slimmest profiles ensure they seamlessly integrate with architectural elements and complement interior decor.

Advanced LED video wall with MicroLED models in 0.6, 0.7 and 0.9mm pixel pitches, and 1.2mm pixel pitch standard LED; with powerful processing, proprietary alignment technology and off-board electronics.

From cinema content to motion-based digital art, Planar® Luxe MicroLED Displays offer a way to enrich distinctive spaces. HDR support and superior dynamic range create vibrant, high-resolution canvases for creative expression and entertainment. Leading-edge MicroLED technology, design adaptability and the slimmest profiles ensure they seamlessly integrate with architectural elements and complement interior décor.

Advanced LED video wall with MicroLED models in 0.6, 0.7 and 0.9mm pixel pitches, and 1.2mm pixel pitch standard LED; with powerful processing, proprietary alignment technology and off-board electronics.

LED video wall solution with advanced video wall processing, off-board electronics, front serviceable cabinets and outstanding image quality available in 0.9mm pixel pitch

Planar® CarbonLight™ VX Series is comprised of carbon fiber-framed indoor LED video wall and floor displays with exceptional on-camera visual properties and deployment versatility, available in 1.9 and 2.6mm pixel pitch (wall) and 2.6mm (floor).

Carbon fiber-framed indoor LED video wall and floor displays with exceptional on-camera visual properties and deployment versatility for various installations including virtual production and extended reality.

a line of extreme and ultra-narrow bezel LCD displays that provides a video wall solution for demanding requirements of 24x7 mission-critical applications and high ambient light environments

Since 1983, Planar display solutions have benefitted countless organizations in every application. Planar displays are usually front and center, dutifully delivering the visual experiences and critical information customers need, with proven technology that is built to withstand the rigors of constant use.

Parker Chomerics offers a wide variety of touchscreen, window and LCD solutions for military, medical, aerospace, and industrial display applications. Providing turnkey solutions with integrated assemblies aids in fast design cycles and fast to market product development cycles.