15 Sep
Displays

How to choose a TFT LCD Display Module?

TFT (Thin Film Transistor) LCD (Liquid Crystal Display) dominates the world flat panel display market now. Thanks for its low cost, sharp colors, acceptable view angles, low power consumption, manufacturing friendly design, slim physical structure etc., it has driven CRT(Cathode-Ray Tube) VFD ( Vacuum Fluorescent Display) out of market, squeezed LED (Light Emitting Diode) displays only to large size display area. TFT LCD displays find wide applications in TV, computer monitors, medical, appliance, automotive, kiosk, POS terminals, low end mobile phones, marine, aerospace, industrial meters, smart homes, handheld devices, video game systems, projectors, consumer electronic products, advertisement etc. For more information about TFT displays, please visit our knowledge base.

There a lot of considerations for how to choose a most suitable TFT LCD display module for your application. Please find the check list below to see if you can find a right fit.

Size

  • It is the start point for every project. There are two dimensions to consider: outside dimension (width, height, thickness) and AA (active area or pixel area). Orient Display’s standard product line ranges from 1.0” to 32”. Our OLED size can go down to 0.66” which fit for wearable devices.

Resolution

  • Resolution will decide the clearance. Nobody likes to see a display showing pixel clearly. That is the reason for better resolution, going from QVGA, VGA to HD, FHD, 4K, 8K. But higher resolution means higher cost, power consumption, memory size, data transfer speed etc. Orient Display offers low resolution of 128×128 to HD, FHD, we are working on providing 4K for our customers. For full list of resolution available, please see Introduction: LCD Resolution

Aspect Ratio or Orientation

  • Orientation of either landscape or portrait has to be taken into consideration. Beside Aspect Ratio is also very important. You might be satisfied with 4:3 in the past, now, you might be willing to trying wider screen like 16:9 or even 21:9.

Brightness

  • TFT screen brightness selection is very important. You don’t want to be frustrated by LCD image washout under bright light or you drain the battery too fast by selecting a super brightness LCD but will be used indoor only. There are general guidance listed in the table below.

Orient Display offers standard brightness, medium brightness , high brightness, and high end sunlight readable IPS TFT LCD display products for our customers to choose from.

Viewing Angle

  • If the budget is tight, TN type TFT LCD can be chosen but there is viewing angle selection of either 6 o’clock or 12 o’clock. Gray scale inversion needs to be taken of carefully. If a high-end product is designed, you can pay premium to select IPS TFT LCD which doesn’t have the viewing angle issue.

Contrast Ratio

  • It is similar to viewing angle selection, TN type TFT LCD has lower contrast but lower cost, while IPS TFT LCD has much high contrast but normally with higher cost. Orient Display provides both selections.

Temperature

  • Normal TFT LCD displays provide wide enough temperature range for most of the applications. -20 to 70oC. But there are some (always) outdoor applications like -30 to 80oC or even wider, special liquid crystal fluid has to be used. Heater is needed for operating temperature requirement of -40oC. Normally, storage temperature is not an issue, many of Orient Display standard TFT display can handle -40 to 85oC, if you have any questions, feel free to contact our engineers for details.

Power Consumption

  • Power consideration can be critical in some hand-held devices. For a TFT LCD display module, backlight normally consumes more power than other part of the display. Dimming or totally shutdown backlight technology has to be used when not in use. For some extreme power sensitive application, sleep mode or even using memory on controller consideration has to be in design. Feel free to contact our engineers for details.

Interface

Orient Display provides a wide variety of interfaces, HDMI, RGB, LVDS, MIPI, SPI, RS232 and Parallel MCU(6800,8080).

  • Genetic Interfaces: Those are the interfaces which display or touch controller manufacturers provide, including parallel, MCU, SPI(,Serial Peripheral Interface), I2C, RGB (Red Green Blue), MIPI (Mobile Industry Processor Interface), LVDS (Low-Voltage Differential Signaling), eDP ( Embedded DisplayPort) etc. Orient Display has technologies to make the above interface exchangeable.
  • High Level Interfaces: Orient Display has technologies to make more advanced interfaces which are more convenient to non-display engineers, such as RS232, RS485, USB, VGA, HDMI etc. more information can be found in our serious products. TFT modules, Arduino TFT display, Raspberry Pi TFT display, Control Board.

Touch Panel

Touch panels have been a much better human machine interface which become widely popular. Orient Display has been investing heavy for capacitive touch screen sensor manufacturing capacity. Now, Orient Display factory is No.1 in the world for automotive capacitive touch screen which took around 18% market share in the world automotive market.

Orient can provide the traditional GG (Glass Glass) touch screen, OGS (One Glass Solution) touch screen, and PG (Plastic Glass) touch screen.

Based on the above three types of touch panel technology, Orient Display can also add different kinds of features like different material glove touch, water environment touch, salt water environment touch, hover touch, 3D (force) touch, haptic touch etc. Orient Display can also provide from very low cost fixed area button touch, single (one) finger touch, double finger (one finger+ one gesture) touch, 5 finger touch, 10 points touch or even 16 points touch

Considering the different shapes of the touch surface requirements, Orient Display can produce different shapes of 2D touch panel (rectangle, round, octagon etc.), or 2.5D touch screen (round edge and flat surface) or 3D (totally curved surface) touch panel.

Considering different strength requirements, Orient Display can provide low cost chemical tampered soda-lime glass, Asahi (AGC) Dragontrail glass and Corning high end Gorilla glass. With different thickness requirement, Orient Display can provide the thinnest 0.5mm OGS touch panel, to thickness more than 10mm tempered glass to prevent vandalizing, or different kinds of plastic touch panel to provide glass piece free (fear) or flexible substrates need.

Of course, Orient Display can also offer traditional RTP (Resistive Touch Panel) of 4-wire, 5-wire, 8-wire through our partners, which Orient Display can do integration to resistive touch screen displays.

Fully, Partial or Semi-Custom Solution

If you can’t find a very suitable TFT LCD Display in our product line, don’t be discouraged. The products listed on our website is only small part of standard products. We have thousands of standard products in our database, feel free to contact our engineers for details.

If you like to have a special display, Orient Display is always flexible to do partial custom solution. For example, to modify the FPC to different length or shape, or use as fewer pinouts as possible, or design an ultra-bright LCD display, or a cover lens with your company logo on it, or design an extreme low power or low cost TFT display etc. our engineers will help you to achieve the goals. The NER cost can start from hundreds of dollars to Thousands. In rare case, it can be tens of thousands of dollars.

A fully custom TFT LCD panel can have very high NRE cost. Depending on the size of the display, quantity and which generation production line to be used. The tooling cost can start from $100,000 to over $1M.

If you have any questions about Orient Display technologies and products, feel free to contact our engineers for details.

 

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15 Sep
Displays

Pros and Cons of TFT Displays

TFT (Thin Film Transistor) LCD (Liquid Crystal Display) we are talking here is TN (Twisted Nematic) type TFT displays which is align with the term in the TV and computer market. Now, TFT displays have taken over the majority of low-end color display market. They have wide applications in TV, computer monitors, medical, appliance, automotive, kiosk, POS terminals, low end mobile phones, marine, aerospace, industrial meters, smart homes, consumer electronic products etc. For more information about TFT displays, please visit our knowledge base.

Talking about Pros and Cons of TFT displays, we need to clarify which display they are compared to. To some displays, TFT displays might have advantages, but compared with another display, the same character might become the disadvantages of TFT displays. We will try our best to make clear as below.

Pros of TFT Displays

  • Less Energy Consumption: Compared with CRT(Cathode-Ray Tube) VFD ( Vacuum Fluorescent Display) and LED (Light Emitting Diode) display, which made laptop possible.
  • Good visibility and color: Compared with old CSTN (Color Super Twisted Nematic) or passive LCDs
  • Good response time and viewing angle: Compared with old CSTN or passive LCDs
  • Good cost: Compared with high end IPS (In-Plane Switching) LCD displays, AMOLED (Active Matrix Organic LED) displays and recent micro-LED display.
  • Excellent physical design. TFT displays are very easy to design and integrated with other components, such as resistive and capacitive touch panels (RTP, CTP, PCAP) etc.
  • Minimum Eye Strain: Because TFT panel itself doesn’t emit light itself like CRT, LED, VFD. The light source is LED backlight which is filtered well with the TFT glass in front for the blue light.
  • Space efficient design (can be placed anywhere in your workspace on a rotational mount so you can turn it in all directions).

Cons of TFT Displays

  • More Energy Consumption: Compared with monochrome displays and OLED (PMOLED and AMOLED) display, which makes TFT displays less attractive in wearable device.
  • Poor color saturation: Compared with IPS LCD displays and AMOLED displays.
  • Poor response time and viewing angle: Compared with IPS LCD displays, AMOLED displays and recent micro-LED display. TFT displays still need to note viewing angle of 6 o’clock or 12 o’clock in the datasheet and still have the gray scale inversion issue.
  • High tooling cost: Depending on which generation production line to produce and also depending on its size. Building a TFT display fab normally need billions of dollars. For a big size display which needs high generation production line to produce. The NRE cost can be millions dollars.
  • Sunlight Readability: Because it is very expensive to produce transflective TFT LCD displays, in order to be readable under the sunlight, very bright LED backlight (> 1,000 nits) has to be used. The power needed is high and also need to deal with heat management. If used together with touch panel, expensive optical bonding (OCA or OCR) and surface treatment (AR, AF) technologies have to be used.

If you have any questions about Orient Display technologies and products, feel free to contact our engineers for details.

 

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08 Sep
Control Board, Displays

How to use Graphic LCD Displays with Raspberry Pi?

How to connect Graphic LCD to Raspberry PI?

The article shows how to hook up a 128×64 graphics LCD display to a Raspberry Pi.

LCD used is a 128×64 with LCD controller of ST7565. It can be powered directly from the Raspberry Pi 3.3V rail. It requires 5 GPIO pins for data.

The schematic is, CS (Chip Select), RST(Reset) and A0 (Register Select) can be connected to any 3 GPIO pins. In this example, 8,24 and 25 are default values. Different values can be specified as parameters when instantiating the ST7565 Python class. SCLK (Serial Clock) on the GLCD goes to GPIO 11 which is the Pi’s serial clock. SID (Serial Input Data) on the GLCD goes to GPIO 10 on the Pi which is MOSI. GPIO 10 and 11 must be used for SID and SCLK. Vdd is connected to a 3.3V pin on the PI and the grounds are also connected.

The LCD has a RGB backlight. The LED pins can go to GPIO’s 16,20 and 21. To control the color from the Pi, specifying RGB pins when instantiate the ST7565 class. The resistors must be placed in series to limit the current to prevent LED breakdown. The LED brightness can be changed by using different values of resistors. It will be best to adjust the current to be around 20mA, of course, different values will result in a different mix of colors. It is very difficult to mix a pure white color. Please calculate the resistor value carefully, at 40mA, the LED brightness will decrease sharply with time, with the current of close to 60mA, the LED might be breakdown and be permanently damaged.

How to program a Graphic LCD?

The display is 128 pixels horizontal by 64 pixels vertical. The LCD can be broken into 8 horizontal pages. They are numbered from 3 to 0 and 7 to 4 up to down. Each page includes 128 columns and 8 rows of pixels. To address the pixels, specifying the page and column number, and send a byte to fill 8 vertical pixels at once.

The display has SPI (Serial Peripheral Interface) to connect to Pi. SPI requires 3 lines MOSI, MISO and Clock. The Pi is the master and the GLCD is the slave. In this example, Only writing to GLCD and not ready, so the connection to MOSI and Clock lines are needed. MOSI is the output from the Pi to the GLCD and the Clock synchronizes the timing.

  1. Enable SPI on Raspberry Pi first
  2. From the raspi-config menu, select Advanced Options, then SPI. Then select Yes for “ Would like the SPI interface to be enabled”. Hit OK, Reboot. Select Yes for “ the SPI kernel module to be loaded by default”. Reboot the Pi after enabling SPI. Then test SPI using IsmodIt should return SPI_bcm2708 or spi_bcm2835 depending on the Pi version. The python SPI library requires python2.7 dev which can be installed with apt-get install:
  3. The Python SPI library is called py-spidev. It can be installed using git:GLCD Python library for the Pi can be downloaded from the GitHub site.
  4. The main ST7565 library (st7565.py) handles drawing, text & bitmaps, and a font module (xglcd_font.py) to load X-GLCD fonts. Here are the basic drawing commands which to create points, lines, rectangles, circles, ellipses, and regular polygons:For more details, please refer to the reference below or contact our engineers.
23 Jul
Displays

TFT LCD Panel (Glass) Manufacturers Introduction

TFT LCD Panel (Glass) Manufacturers Introduction

 

 

Starting from the 2nd quarter of 2021, the LCD panel prices have kept increasing. We expect that the high prices will keep for at least 6 months. There are a lot of manufacturers of making LCD modules but there are only a few LCD panel or LCD glass manufacturers in the world. The reasons are 1) In order to build a LCD panel fab, billions of dollars of the equipment investment is needed; 2) The technology threshold is high. There are a lot of patent traps on the way; 3) Once in production, the fab has to keep running otherwise it is easy to lose money because of the heavy investment and the high pay for the engineers; 4), The worst is that the manufacturers have keep on investment in order to keep the technology and price competitive.   Let’s take a look of these LCD panel manufacturers.

AUO (AU Optrinics Corporation，友达光电):

In Taiwan.  It was formed in 2001 by the merger of Acer Display Technology Inc and Unipac Optoelectronics Corporation. It has G3.5 to G8.5 production lines.

 

BOE (Beijing Oriental Electronics Group Co., Ltd，京东方):

In China. The biggest LCD panel manufacturer in the world now.  BOE has G4 (Chengdu), G5 (Beijing), G5.5 (Ordos), G6 (Hefei, Chengdu, Mianyang, Dalian), G8 (Beijing, Hefei, Chongqing), Fuqing, Dalian, Chongqing) and 10.5 (Hefei) production lines.

 

CSOT (China Star Optoelectronics Technology，华星光电):

In China. It was joint ventured by TCL and Shenzhen Government. It mainly focusses on TV and cell phone screens. It has G6 (Shenzhen), G8.5 (Shenzhen, Suzhou,Wuhan) and G11 (Shenzhen) production lines.

 

CSOT (China Star Optoelectronics Technology,华星光电):

In China. It was joint ventured by TCL and Shenzhen Government. It mainly focusses on TV and cell phone screens. It has G6 (Shenzhen), G8.5 (Shenzhen, Suzhou,Wuhan) and G11 (Shenzhen) production lines.

 

CTC (Century Technology Shenzhen Co Ltd, 深超光电):

In China. CTC is the joint ventured by Foxconn and Shenzhen Government.  CTC has a G5 production line.

 

Giantplus Technology (凌巨科技):

In China, In 2019, it was acquired by Toppan in Japan. Ortus Technology holds 53.1% Giantplus shares. Giantplus has a G3 and a G4 production lines.

 

Hannstar (HSD, HannStar Display Corporation, 瀚宇彩晶):

In Taiwan. Hannstar has a G5 IPS production line.

 

HKC (惠科股份):

In China. HKC mainly produces LCD panels for monitors. HKC has 4 G8.6 production lines in Chongqing, Chuzhou, Mianyang, Changsha.

 

Innolux Corp (INX, 群创光电):

In Taiwan. One of the daughter company of Foxconn/Hon Hai.  In 2010, it bought the then famous LCD manufacturer, ChiMei, then changed its name to Innolux. It has G7.5 production lines.

 

IVO (InfoVision Optoelectronics (Kunshan) Co.,LTd. 龙腾光电):

IVO mainly produces laptop LCD panels. IVO has G5 production line.

 

JDI (Japan Display Inc, 日本显示):

In Japan. Joint ventured by Sony, Hitachi and Toshiba in 2011. It mainly produces smaller size panels. JDI has G6 production line.

 

Laibo (Shenzhen Laibao Hi-Tech Co.,Ltd, 莱宝高科):

Laibo has a G8.5 (Wuhan) and a G2.5 (Shenzhen) production lines.

 

LG.Philips Displays (LGD乐金电子):

In Korea and China. It is used to be the 2nd biggest TFT LCD manufacturers. LG also planned to stop the production but delayed the plan after the price increased. LG has G7.5 and G8.5 (Guangzhou) production lines.

 

Mantix Display Technology Co.,Ltd (华彩佳):

In China. Original Matix is the partner of CPT (Chunghwa Picture Tubes 中华映管). After CPT filed bankruptcy in 2019, Mantix took over CPT G6 production line.

 

Panasonic (松下):

In Japan. Panasonic has a G8.5 production line.

 

Panda (Nanjing CEC Panda LCD Technology Co.，Ltd. ,中电熊猫):

In China.  It got the technology from Sharp. It mainly produces LCD panels for TV.

 

Samsung Display （SDC,三星显示):

In Korea. It used to be the biggest TFT LCD manufacturers before it was dethroned by BOE in 2019. Because of tough competition, Samsung planned to stop the production in 2021 but delayed because the price increase during the pandemic.  Samsung has G7 and G8.5 production lines.

 

Shanghai Hehui Photoelectric Co., Ltd (上海和辉光电):

Hehui also produces AMOLED only and It has a G4.5 LTPS AMOLED production line.

 

Sharp （夏普):

In Japan and China. The pioneer and queen of LCD industry. Because of high cost and tough competitor, Sharp was acquired by Foxconn/Hon Hai in 2016. Sharp has G8, G8.5(Suzhou), G10, G10.5 (Guangzhou) production lines.

 

Tianma Microelelctronics（TM,天马微电子):

In China and Japan. In 2011, Tianma acquired 70% share from NEC to rename as “NLT Technologies”. Tianma has G4.5 (Shanghai, Chengdu, Wuhan), G5 (acquired from SVA: SVA Information Industry Co.,Ltd.). G5.5 (Xianmen, Shanghai for AMOLED),  G6 (Xiamen, Wuhan for AMOLED).

 

Truly Opto-electronics (信利光电):

In China, Truly was mentioned to have a G4.5 for AMOLED and a G2.5 for TFT LCD production lines.

 

Visionox (维信诺):

Actually, Visionox doesn’t product LCD. It produces AMOLED and PMOLED only. It has a G5.5 AMOLED and a G6 flexible AMOLED production lines.

LCD Motherglass Generation Classifications
Generations Motherglass Size Notes
G1 320*400 \
G2 370*470 \
G3 550*650 15″/4pcs
G4 680*800 15″/6pcs
G4.5 730*920 15″/8pcs
G5 1100*1300 27″/6pcs
G5.5 1300*1500 27″/8pcs
G6 1500*1850 32″/8pcs, 37″/6pcs
G7 1950*2250 42″/8pcs, 46″/6pcs
G8 2160*2460 46″/9pcs, 52″/6pcs
G8.5 2200*2500 55″/6pcs
G10 2880*3100 65″/6pcs, 60″/8pcs
G10.5 2940*3370 65″/8pcs
G11 3000*3320 70″/8pcs

 

23 Jul
Displays

Impact of Semi-Conductor Shortage on Display Manufacturers

Impact of Semi-Conductor Shortage on Display Manufacturers

Starting from June 2020, the LCD panel prices started increasing. By the end of 2020, the average panel price increased 50-70%. IC prices following the panel price increase. We saw the 1st wave of IC price increase starting the 3rd quarter 2020, and the 2nd wave around February 2021. Worse than price increase, the panel and IC shortage has become serious issue for many manufacturers. GM, Ford and other car makers idled their production and cut production which affects their earnings. Even the newly elected president Biden ordered supply chain review in the first month in his office. What are the reasons of LCD panel and IC frenzy become the global crisis?

 

 

The Reason for the crisis

 

  • – Pandemic: The direct and root cause of causing the crisis is the pandemic.  In March 2020, a lot of countries issued executive orders for people to stay at home. The demand for various products dropped sharply. A lot of manufacturers cancelled or pushed out orders.  The world 1st and 2nd biggest LCD manufacturers Samsung and LG declared the plan to stop all the LCD production. A lot of LCD panel and IC manufacturers cut the production because of order drop or executive orders to stay at home. They use stock instead of the fresh production to fill the demands.

 

  • – Chaos of Executive orders and planning: Because of the pandemic, nobody knew what was ahead.  Executive orders were updated monthly, the same as the planning for schools, plants, companies and other organizations. By July, a lot of schools started to realize that it was not practical to open the schools in personal and needed every student to have online classes which suddenly boosted the orders of laptops, monitors, TVs and other entertainment devices. The LCD panel manufacturers couldn’t ramp up for so fast increased demands. The stock was cleared quickly and LCD factories had been running 7/24 starting last fall which still couldn’t keep up the order speed. The price increase followed right after.

 

  • – Zero Stock Policies: LCD panel and IC prices had been inclined for more than a decade. There had been a fixed mindset for a lot of commodity executives and managers that the prices will fall ever. Because the competition was tough for suppliers, the big customers demand for OTD (On Time Delivery), especially for automotive makers. They don’t hold much or any stock in order to improve the cost down and cash flow. The result is that they totally rely on suppliers to hold the inventory. With the pandemic, a lot of customers first pushed out orders which made the supplier chill in spine. The suppliers tried to cut their inventory in order to prepare enough cash for industrial winter.

 

  • – Panic: A lot of companies had fixed mindset that they could ask the suppliers to shorten lead time and keep supplying with many years free of issues. When they suddenly realized that the old practices could cause their production line down situation, most of them were in panic and ordered much more than they really need. The quantities were suddenly piled up to unreasonable situation.  Most of the IC manufacturers issued notices to the customers that their orders NCNR (Not Changeable and Not Cancellable) trying to prevent the unreasoning orders.

 

  • – Stimulus Packages: Government of many countries have been racing to issue stimulus packages and money flood the market. It is true that some people were struggling to stay away hunger. But most of the governments didn’t identify the real needed people. They used the ways of helicopter distributing money. A lot of people used the money to upgrade their household and entertainment.  As most of the governments promised supplying the money unlimited to the market without any cap, the majority of the companies and personals are free of worries and expect the governments will always come to rescue if they are in trouble. The competition of spending is flooding.

 

Consequences

 

  • – By the end of 2020, the LCD panels for TV increased 32” 119%, 43” 81%, 55” 84%, 65” 46%.

 

  • – By the end of 2020, LCD controllers/driver prices increased around 20%. By March 2021, the prices increased 20-30% again. The IC shortage made many factories line down. The IC prices in distributions and after market are even higher.  There was a blog mentioned a STmicro MCU price increased from 5 yuan to 70 yuan.

 

  • – The prices of materials used for LCD production increased too.  ITO glass, polarizer, FPB, PCB, packing material, photoresist, chemicals etc.

 

  • – The prices of other components increased too. Resistors, capacitors, LED, etc.

 

  • – The commodity prices increased too, copper, nickel, plastic (oil), water, electricity.

Forecast

 

  • – We believe that the production capacity of LCD panels and ICs are largely balanced with the real market demands. With the frenzy over, the prices will drop eventually.

 

  • – The LCD panel price increase is still slowdown. We believe the LCD panel price will keep flat but still at the high price level in 3rd and 4th quarter 2021. It is no benefit for LCD panel manufacturers with price drop if the IC is still in tight supply. We should see LCD panel price drop in 2nd quarter 2022. The price drop speed should accelerate in 4th quarter 2022. Super-hot will create super cold. We believe we will see LCD panel winter in 2023 which should last 2-3 years.

 

  • – IC is still in rapid price increase.  It is our predication that IC price should stop increase in 2nd quarter 2022. We should see the price drop starting on 4th quarter 2022.

 

  • – The biggest threat in the market is that the real market is not big. Most of the companies ordered too much, they might cancel some of the orders.  When we see some customers start to cancel the orders, it is the same to see the first leave falling, the fall comes. The tread will accelerate like dominos. The winter for the industry will come.

 

  • – We see this wave of frenzy as man-made. The governments have been printed too much money. Inflation is inevitable.

 

23 Jul
Displays

Are LCD screens dangerous?

Are LCD Screens Dangerous?

LCD (liquid crystal display) consumes much less power, and is lighter, thinner than CRT (Cathode Ray Tube). It is the most popular display technology in the world now.  It has been widely used in mobile phones, tablets, TVs, laptops, computer monitors, ATMs, Kiosks, home appliances, IoT, automotive, solar panels etc. The sizes are getting bigger and the quantities are getting more. There are a lot of worries about if LCD screens safe or even dangerous or any affect for the climate change? There was little research on it. There are several articles on the internet with contradictory information.  It is important to look at the safety issue from a viewing angle from a LCD panels professional manufacturer.  In order to have deep understand of the question, we have to have a deep understanding of the LCD basis. As most of the big size LCDs are color display, we will focus on TFT LCDs.

Introduction to LCD Displays: TFT LCD Structure and How it works

TFT LCD Display (Thin-Film-Transistor Liquid Crystal Display) technology has a sandwich-like structure with liquid crystal material filled between two glass plates. Two polarizer filters, color filters (RGB, red/green/blue)and two alignment layers determine exactly the amount of light is allowed to pass and which colors are created. Each pixel in an active matrix is paired with a transistor that includes capacitor which gives each sub-pixel the ability to retain its charge, instead of requiring an electrical charge sent each time it needed to be changed.  The TFT layer controls light flow a color filter displays the color and a top layer houses your visible screen. See Fig.1 for  TFT LCD structure.

 

Fig.1 TFT LCD Display Structure

Utilizing an electrical charge that causes the liquid crystal material to change their molecular structure allowing various wavelengths of backlight to “pass-through”. The active matrix of the TFT display is in constant flux and changes or refreshes rapidly depending upon the incoming signal from the control device. 

The pixels of TFT displays are determined by the underlying density (resolution) of the color matrix and TFT layout. The more pixels the higher detail is available. Available screen size, power consumption, resolution, interface (how to connect) define the TFT displays.

TFT screen itself can’t emit light like OLED display, it has to be used with a back-light of white bright light to generate the picture. Newer panels utilize LED backlight (light emitting diodes) to generate their light and therefore utilize less power and require less depth by design.

TFT display module includes TFT display screen, LED backlight and driving circuitry.

OK, let’s analyze one layer by another.

-Polarizers: Actually, polarizer is made of several layers of normal plastic. Mostly they are PVA ( Polyvinyl alcohol ) and TAC (three cellulose acetate film). Both are normal safe polymer. Most of the plastic nowadays has  flame retardants to prevent from catching fire.Fig. 2 Polarizer Structure

 – Glass: Normally, there are two kinds of glass used: Soda lime and alkalinebosicate. Both are safe.-TFT: It’s kind of semiconductor which mainly has silicon and metal (gold, aluminum etc.). They are safe.

 – Color Filter: They are very thin and are made of polymers of photoresist. The process is done by photolithography method. They are safe.

 – Driving Circuitry: LCD’s driving circuitry has no material different from other electronics. It has IC (Integrated circuit) and PCB (Printed Circuit Board).

 – Backlight and Liquid Crystal Material: Both are the most suspicious. We will dive deep into these two parts.

Mercury Vapors

Some internet articles claimed that the LCD screen uses mercury to generate visible light as part of the viewing process. It is the reason that there is a chance that vapors could escape where the screen becomes cracked. While the mercury levels are generally low, there is a risk of side effects such as allergic reactions, skin rashes and even birth defects.

To our understanding, it is a false statement. From our above structure analyze, LCD screen doesn’t contain mercury at all.  LCD screen can’t light itself; it has to use light source to help it to be seen. The light sources can be sunlight, surrounding light or we can make backlight at the back of the LCD screens.

There are two kinds of backlight: LED (Light Emitting Diode) backlight and CCFL (Cold Cathode Fluorescent Lamp) backlight. Both are widely used for our normal lighting at home. If LCD screen and mercury have to be related. It can be the CCFL which contains toxic metals and their salts, including mercury to produce fluorescent light. But you might notice that most of LCD manufacturers advertise LED displays which are LED backlighted LCD displays.  Orient Display stopped using CCFL as backlight 15 years again and we are 100% RoHS (Restriction of Hazardous Substances Directive) Compliance for whole factory including raw materials, process and products.

Fig. 3 ROHS Compliant

 

Liquid Crystal Material

Liquid crystal is a state between liquid (like water) and crystal/solid (like ice). Although we have liquid crystal displays around us, most of people never see what liquid crystal materials look like. Actually, commercial liquid crystal materials look like milk. But you can’t drink it.

Fig. 4 A Bottle of Liquid Crystal Materials

Liquid Crystal monomers don’t have protein. Their chemical structures look like below. The effect of these chemicals shows in MSDS (Material Safety Data Sheet).

Fig. 5 Liquid Crystal Material Typical Formula

 

Environmental Impacts

Some researchers have a deep study into chemicals used in LCD display and the result is as below:

– In Proceedings of the National Academy of Sciences, Giesy’s research team assembled and analyzed a comprehensive list of 362 commonly used liquid crystal monomers gathered from 10 different industries and examined each chemical for its potential toxicity. When inhaled or ingested, these toxic chemicals can build up in the body over time with toxic effects, potentially causing digestive problems and other health issues.

-“These chemicals are semi-liquid and can get into the environment at any time during manufacturing and recycling, and they are vaporized during burning,” said University of Saskatchewan environmental toxicologist and lead author John Giesy in a press release. “Now we also know that these chemicals are being released by products just by using them.”

-The researchers found the specific monomers isolated from the smartphones were potentially hazardous to animals and the environment. In lab testing, the chemicals were found to have properties known to inhibit animals’ ability to digest nutrients and to disrupt the proper functioning of the gallbladder and thyroid–similar to dioxins and flame retardants which are known to cause toxic effects in humans and wildlife.

-To be clear, the researchers didn’t observe any adverse health effects from the accumulation of liquid crystals in the human body; they only found that these crystals do in fact leak from devices, and that they have the potential to be toxic. “We don’t know yet whether this a problem, but we do know that people are being exposed, and these chemicals have the potential to cause adverse effects,” said Giesy.

OK, relax. If you understand the research statement above correctly and combine our understanding of liquid crystal materials. The results are:

-Any artificial chemicals have potential hazard to human health. If you read the notes of your prescription drug, the statement is likely more alarming than above.

-Don’t burn your LCDs, just like you can’t burn your battery, your wires or gasoline. Any vapor can be hazard.

-If you crack LCD screens and find the liquid crystal leakage, don’t panic. Just remember that the liquid crystal materials might not be more toxic than your detergents for stove or washroom. Just wash your hands with soup throughout. Never try to play with it or even worse to taste it. The liquid of the cracked computer screen will not evaporate, no emissions worries.

-Any electronics has environment impact and can’t be used landfills. If you want to get rid of old LCD monitors or LCD TVs, give them to electronic collection stations. Let’s the professionals to handle them. They will extract some precious metals/parts and make them into something useful or at least not hazard. FYI, liquid crystal materials are retrievable. 

 

Other Impacts 

-Will LCD screen emit ultraviolet radiation or blue light?

No, LCD screen doesn’t emit light itself. It uses LED backlight to produce visible light which doesn’t have the either UV or Blue light wavelengths.

-My Samsung uhd 65-inch LCD TV cracked. Can it be repaired? .

No, the LCD is made by glass which can’t be repaired. Please send the TV to your local waste management company for recycling.

-I heard that LCD screen can damage ozone layer, is it true?

Many year ago, LCD manufacturing process used hydro-fluorocarbons as solvent, which can damage ozone layer. Now, it is prohibited to use this chemical.

 

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