Cut TFT displays

In the world of display technologies, displays are increasingly being tailored specifically to applications. This is why so-called "cut TFT displays" are increasingly being used, particularly in space-critical designs or in the HMI sector for industrial control systems. By cutting standard TFT cells, unusual formats can be achieved without expensive tooling. But how does this actually work? And what are the risks associated with this approach?

Cut displays are modules in which a standard TFT LCD panel is subsequently cut to a customer-specific size. This is usually done with TFT LCDs that were originally manufactured for a larger standard resolution.

As a rule, the panel is only cut on one side, opposite the contact strip (FPC/COF). This leaves the control and control electronics intact. However, this also means that the output size of the panel must be chosen carefully so that the resulting format meets the requirements for size (in inches) and resolution.

After cutting, the open edge is sealed with a special adhesive to prevent the liquid crystal from leaking out. This process is technically demanding because the glass substrate is sensitive and the sealing step must be performed perfectly to ensure long-term tightness and stability.

TFT displays are usually cut using highly specialized laser processes. The following aspects must be taken into account:

• Precision: The substrate (usually glass) must be separated with micrometer precision without destroying the pixel structure or conductor tracks.
• Protective layers: Polarizing films, touch panel layers, and any light filters must then be adjusted or replaced.
• Electronics: The control system (driver ICs) must not be impaired.
• Backlighting: In many cases, the backlighting must be readjusted or partially reconstructed, which poses additional challenges in terms of display brightness and uniformity.

The rejection rate is high, as even minimal cracks in the glass or impurities render the entire module unusable. Handling the sensitive glass substrates requires a great deal of experience and special equipment.

1. Reliability:
   • Cut TFT displays may be more susceptible to failure due to microscopic damage.
   • Long-term stability and response time are often not documented or tested.
2. Costs:
   • The committee and the effort required for follow-up work lead to significantly higher unit prices.
   • There are often one-time costs for cutting and qualification.
3. Patent protection:
   • Various patents exist in the EU and the USA in the field of TFT manufacturing and post-processing.
   • Subsequent cutting of displays may violate property rights, especially if this is done outside of licensed production processes.
   • The American patent in particular is very strict, so caution is advised when exporting to the USA.
4. EMC and electrical properties:
   • Removing edge structures may impair electromagnetic compatibility (EMC).
   • Capacitive touch is often sensitive to mechanical modifications.

Instead of cut displays, so-called bar-type TFTs are increasingly recommended. These are already designed ex-works for a long, narrow format, e.g., 12.3", 7.84", or 4.6" with resolutions such as 1280×200 or 480×128 pixels.

• Industrially tested and reliable
• Long-term availability thanks to established manufacturers and defined supply chains
• No risk regarding patents or reworking
• Less effort required for integration and certification
• Optimized modules with coordinated backlighting and touch panel options

criterion	Cut TFT displays	Bar-type TFTs
format flexibility	Very high – free length cuts possible	Medium – depending on available formats
Customization	Possible, but technically complex	Limited, but many variants now available
Technical effort	Very high – laser cutting, sealing, adjustment of backlight and touch if necessary	Low – ready-made modules, ready for integration
Reliability / Quality	Limited – risk of microdamage, less documented	High – industrially tested, documented specifications
production committee	Highly sensitive cutting process	Low – standardized manufacturing
Cost	High – one-time costs + high unit prices due to rejects	Economical – stable prices through series production
Legal risks (patents)	High – especially in the US and EU	None – Use of licensed designs
Long-Term Availability	Uncertain – depending on initial panel	Uncertain – Medium – Depends on the panel and application
EMC & electrical properties	Affected by edge loss	Optimized – EMC-compliant designs
Typical Applications	Special solutions with extreme space requirements	Industrial displays, control systems, infotainment

Cut TFT displays can be a solution in special cases, but they carry considerable risks in terms of reliability, cost structure, brightness, and legal certainty. Careful consideration is necessary, especially in professional applications.

If you want to be on the safe side, you should opt for standardized Bartype TFTs, which are now available in many sizes, resolutions, and variants and represent a robust, economical solution for a wide range of applications.

Diagonal	Type	Part No.	Active Area	Resolution	External Dimensions	Brightness	Interface	Touch	Operating Temp	Technology
0.96	Bar Type TFT	LCD096LAB-02-100N	10.8×21.696	80×160	13.8 × 28.0 × 1.9	400	SPI			IPS,ALL
1.08	Bar Type TFT	LCD108LAA-01-100N	22.7×42.72	128×220	17.12 × 29.76 × 1.6	350	serial			IPS,ALL
1.9	Bar Type TFT	LCD190LAB-01-100N	22.7×42.72	170×320	25.8 × 49.72 × 1.43	350	serial			IPS,ALL
1.99	Bar Type TFT	LCD199LAA-01-100N	22.7×42.72	170×320	25.8 × 49.72 × 1.43	600	serial			IPS,ALL
2.18	Bar Type TFT	LCD218LAB-01-100N	21.72×52.416	200×480	25.72 × 59.49 × 2.3	250	MIPI			IPS,ALL
2.18	Bar Type TFT	LCD218LAB-01-100N	21.72×52.416	200×480	25.72 × 59.49 × 2.3	250	MIPI		-20 +70	IPS, ALL
2.41	Bar Type TFT	LCD241LAA-01-100N	30.192×53.28	272×480	33.89 × 60.32 × 2.18	500	MIPI			IPS,ALL
2.86	Bar Type TFT	LCD286LAA-02-100N	26,508×67.68	376×960	31.2 × 76.6 × 2.1	200	SPI/RGB			IPS,ALL
3.9	Bar Type TFT	LCD390LAB-01-100N	95.04×25.35	480×128	105.24 × 37.8 × 3.6	420	RGB			IPS,ALL
3.99	Bar Type TFT	LCD399LAA-01-100N	39.18×94.032	400×960	44.4×103.88×2.2	280	RGB			IPS,ALL
3.99	Bar Type TFT	LCD399LAA-01-100N	39.18×94.032	400×960	44.4×103.88×2.2	280	SPI/RGB		-20 +70	IPS, ALL
4.58	Bar Type TFT	LCD458LAA-01-100N	26.77×110.3	320×960	41.57 × 118.8 × 2.5	300	RGB			IPS,ALL
5.19	Bar Type TFT	LCD519LAA-01-100N	40.75×125.38	416×1280	45.15 × 132.58 × 3.54	400	MIPI			IPS,ALL
6.1	Bar Type TFT	LCD610LAA-01-100N	29.99×152.51	280×1424	33.99 × 160.31 × 2.8	220	MIPI			IPS,ALL
6.86	Bar Type TFT	LCD620LAA-01-100N	148.8×53.76	640×240	164.1 × 72.06 × 3.65	430	RGB			IPS,ALL
6.86	Bar Type TFT	LCD686LAB-01-100N,C	60.19×160.51	480×1280	67.0 × 181.4 × 5.0	600	MIPI	Capacitive		IPS,ALL
6.9	Bar Type TFT	LCD690LAA-01-100N	33.6×170.88	280×1424	38.2 × 181.47 × 3.54	400	MIPI			IPS,ALL