Analysis Of Three New Low-cost Designs For LCD TV Panels

DisplaySearch pointed out that in the past year or so, the sales price of the panel has always been lower than the production cost, which is also the biggest challenge faced by TFT LCD panel manufacturers. Long-term deficits not only consume their cash, but also deplete their belief in the future development of the TFT LCD and TV industry. In order to change the current situation, panel manufacturers are trying different ways: such as reducing costs and specifications. This approach is completely different from always introducing the latest and best features and specifications for the end consumers before and trying to reduce the price to stimulate consumption. There are three different ways of such innovation:

Develop a low-cost direct-lit LED backlight system with below-average brightness

Developed a thick TV panel for CCFL backlight system

Replace the original 120 Hz double frame rate technology with 60 Hz plus scanning backlight technology.

These new methods are still under development, but we can expect TV brand manufacturers to adopt these innovative products, and soon see it being introduced into the low-end consumer market. The estimated time point is early 2012. Interestingly, these efforts target not only emerging markets such as China, South America, Eastern Europe, and Southeast Asia, but also developed countries such as North America and Western Europe. Obviously, the dull market atmosphere in developed countries convinces end consumers that budget control is more important than brand-name TVs. Moreover, consumers who are willing to accept low-spec TVs because of their limited budget can be found anywhere in the world.

The following table describes the main advantages and disadvantages of these three innovative methods, and the opportunities and risks that panel manufacturers will face.

Table 1. 2012 low-end LCD TV SWOT analysis

Low cost direct type LED backlight module

Most people understand that the cost of direct-lit LED backlights is higher than the currently popular side-edge LED backlights. When the supply chain first introduced LEDs to the LCD TV panel backlight module, it was a direct-lit LED backlight application. From the viewpoint of environmental protection, the direct-lit LED type is superior to CCFL. The characteristic of LED is that it has lower power consumption, and the dimming ability can improve the contrast to achieve better picture performance. However, early developers like SONY did not succeed in introducing the direct-lit LED backlight into the mainstream because it was too expensive. The high cost is due to the large number of LEDs used in the backlight module in an arrangement or array.

The edge-lit LED backlight module developed by Samsung Electronics has surprised the entire industry. This new concept places the LED light bar on the side of the backlight module, which immediately greatly reduces the number and thickness of LED particles. The new edge-lit LED backlight module design is comparable to the old direct-lit LED backlight.

Edge-lit LED backlights have enabled panel manufacturers to successfully reduce the number of LEDs by using LEDs with better luminous efficiency and increasing the light transmittance of the panel. In most backlight modules, LED light bars have been reduced from six to two. According to DisplaySearch's large-size TFT LCD panel technology blueprint research report, panel manufacturers are currently researching and developing to reduce the number of LED light bars to one, especially Samsung Electronics, the developer of advanced edge-lit LED backlights.

However, panel manufacturers have always had a headache that the price of LEDs is higher than that of traditional CCFLs, and end consumers are only willing to accept low-priced LEDs. Panel manufacturers have no choice but to continuously reduce the price of LED panels, which prompts them to think about new ways.

The LED backlight module development engineers of panel manufacturers have found the following new ideas that can realize lower-cost LED backlights, especially the cost is lower than the current edge-lit LEDs:

Concept: Replace CCFL with low-cost LEDs without changing the current mechanical structure of CCFL backlight.

Goal: Divide into 32 "CCFL HD Volume Zones" and use it to accelerate LED penetration.

Challenge: LED means ultra-thin, end consumers may be confused by thick LED models.

The following table compares the direct-lit CCFL with the edge-lit LED.

Table 2. Comparison of the new direct-lit low-cost LED backlight with CCFL and edge-lit LEDs

The concept is to use larger LED chips, which are still arrays, but with fewer arrays. The LED package is coated with a special reflective lens to further improve the luminous efficiency, so fewer LEDs can be used. A thicker backlight module is necessary, because the light of the LED needs enough space for refraction, so it is about the same thickness as a traditional CCFL backlight module.

The biggest advantage of direct-lit LEDs is that the light guide plate (LGP) can be reduced, resulting in a cost reduction. By removing the brightness enhancement film (DBEF), the cost can be further reduced. Without a light guide plate, a high-efficiency diffuser is a necessity for maintaining brightness uniformity. Another element of this concept is to lower the brightness standard of the panel. In summary, this method creates a direct-lit LED backlight module whose thickness is the same as that of the CCFL model, but the cost is lower than that of an edge-lit LED backlight module. Many TV panel manufacturers are working towards the same cost as the CCFL backlight module when designing this new concept.

This solution is expected to be unveiled in the terminal market in early 2012. Its advantage is definitely cost, especially if its cost is similar to that of CCFL backlight. The biggest challenge is to convince consumers of the value of thick LED models, because most consumers have been educated that “LED” is equivalent to “ultra-thin”. In addition, this approach may require close cooperation between panel manufacturers, LED manufacturers, and backlight module assembly plants.

Since thickness may be the biggest obstacle for end consumers to accept, some panel manufacturers may develop narrow bezels to offset the shortcomings of thickness. In addition, the BMS business model will be widely used, because the integration with BMS may be able to reduce the thickness.

Thick backlight module LCD TV panel

This method is to reduce the number of CCFL and brightness enhancement film (BEF), but the thickness of the panel and the backlight module is increased by changing the structure of the backlight power system. Structural reorganization changes the traditional power board + inverter structure into an Integrated Power Board (IPB) + Transformer Balance Board (T-Balance) structure. Due to the structural adjustment of the power system, the CCFL backlight module will be thicker than before. For example, the thickness of a 32" backlight module will increase from 48 mm to 58 mm. However, this significantly reduces the cost of the backlight power system. Panel manufacturers call these panels CCFL entry, Panda panels, or fat panels . In terms of cost savings, it can be 5 to 7 dollars less than traditional CCFL panels.

Obviously, this panel will need to find a special position, especially in developing countries, where consumers care less about LEDs and thickness than purchase costs. Some Indian buyers said that they would like a thicker panel so that large speakers can be installed in the TV. Many Indian consumers care more about the sound quality of the TV than the image quality.

On the other hand, the challenge of this type of panel is that manufacturers will need to redesign the power supply system of their TV to match it.

60 Hz + scanning backlight module (simulation 120 Hz)

The price difference between 60 Hz and 120 Hz panel cost is at least 10-15 US dollars. The cost increase is related to timing controller (T-CON) and motion estimation/compensation (Motion Estimation, ME / Motion Compensation, MC) technology. However, panel manufacturers thought of a new approach: using scanning backlight to artificially achieve the effect of 120 Hz. The scanning backlight uses the scanning control IC to blink brightness. This is like inserting more related images into the original dynamic movie, so that end consumers will not see the dynamic smear that often occurs at 60 Hz. This method subtracts T-CON and ME/MC costs. Scanning the IC controller is necessary, but the cost is not high.

The end consumer can have a real 120 Hz perception. They will not see the dynamic smear because it is covered by the backlight scan. However, scanning may cause jitter problems.

The working effect of the 60 Hz scanning backlight is not bad, and there is no additional artificial frame rate conversion (Frame Rate Conversion, FRC). Philips tried to use high-cathode fluorescent lamp (HCFL) backlighting in 2006. It is also very cheap because it does not require additional memory to increase the picture. Most importantly, by eliminating 120 Hz, the cost can be reduced by 10-15 US dollars. Therefore, this seems to be good news for panel manufacturers.