Écran TFT LCD personnalisé : spécifications clés à définir avant commande

La façon la plus rapide de retarder un projet d'écran LCD TFT personnalisé est de commencer avec une spécification incomplète.

Une demande telle que “ Nous avons besoin d'un écran industriel de cinq pouces avec tactile ” laisse la majeure partie du travail d'ingénierie non définie. La zone active peut ne pas s'adapter au boîtier. Le processeur peut ne pas prendre en charge l'interface du panneau. Le verre de protection sélectionné peut réduire la luminosité ou la sensibilité tactile. Un connecteur qui fonctionne sur le banc d'essai peut devenir inaccessible après l'assemblage.

Une demande de devis utile décrit le produit autour de l'écran : ce que les utilisateurs doivent voir, où le module doit s'intégrer, comment l'hôte envoie les pixels, quelles limites environnementales s'appliquent et quelles quantités sont attendues.

Ce guide explique les spécifications à définir avant de contacter un fabricant d'écrans LCD TFT. Il montre également où les solutions standard, semi-personnalisées et entièrement personnalisées ont du sens pour les produits industriels, médicaux, automobiles et embarqués.

La Réponse Courte

Avant de commander un module LCD personnalisé, définissez ces dix éléments :

1. Zone d'image visible et encombrement maximal du module
2. Résolution, orientation et contenu de l'interface utilisateur
3. Luminosité, direction de visualisation et environnement d'éclairage
4. Conditions de fonctionnement et de stockage
5. Interface TFT, processeur hôte et exigences de mise à jour
6. Technologie tactile et conditions réelles de l'opérateur
7. Dessin de la lentille de protection, impression et traitement de surface
8. Contraintes de FPC, connecteur, montage et câblage
9. Tests de prototype et critères d'acceptation
10. Quantité pilote, prévision annuelle et période d'approvisionnement requise

Marquez chaque élément comme fixe, préféré ou flexible. Cette distinction simple aide le fournisseur à préserver ce qui compte tout en utilisant une plateforme existante là où ce n'est pas le cas.

Quand devez-vous choisir un Écran LCD TFT personnalisé?

La personnalisation est justifiée lorsqu'un écran standard transfère trop de coûts ou de risques sur le reste du produit.

Par exemple, modifier un outillage de boîtier pour s'adapter à un module standard peut coûter plus cher que de modifier le FPC de l'écran. Un rétroéclairage plus lumineux peut éviter un pare-soleil externe profond. Une lentille de protection personnalisée peut combiner la fenêtre de visualisation, l'image de marque et la surface avant scellée en une seule pièce. Une carte d'interface peut préserver un processeur hôte éprouvé.

Envisagez un écran LCD TFT personnalisé lorsque :

• Aucune zone active standard ne correspond au design industriel
• Le connecteur ou le FPC sort au mauvais endroit
• L'hôte ne prend pas en charge l'interface native du panneau
• La luminosité standard est insuffisante pour l'environnement d'éclairage
• Le produit nécessite une intégration tactile PCAP ou résistive
• Une lentille de protection profilée ou imprimée fait partie du boîtier
• Une liaison optique est requise
• La température de fonctionnement dépasse les configurations standard disponibles
• L'écran doit être fourni en tant que sous-ensemble testé
• Une configuration contrôlée est nécessaire pour un programme produit de plus longue durée

La personnalisation doit résoudre une contrainte documentée. Elle ne doit pas être utilisée simplement pour rendre le numéro de pièce unique.

Trois niveaux de personnalisation

L'expression “ écran personnalisé ” peut décrire des quantités très différentes de travail d'ingénierie.

Module standard avec support de sélection

Le module d'écran reste inchangé. Le fournisseur aide à identifier un modèle existant qui répond aux exigences mécaniques, optiques, électriques et environnementales.

C'est normalement la voie la plus rapide vers un prototype initial. Cela préserve également l'historique d'approvisionnement et de qualification le plus large.

Semi-personnalisé Module TFT LCD

Une plateforme TFT éprouvée reste au centre, tandis que les composants d'intégration changent autour d'elle.

Les travaux semi-personnalisés typiques comprennent :

• Longueur, forme ou affectation des broches du FPC révisées
• Connecteur différent
• Rétroéclairage ou luminosité modifiés
• Panneau tactile personnalisé
• Lentille de protection imprimée
• Collage optique
• Cadre de montage ou adhésif
• Carte de conversion d'interface ou de pilote

Pour de nombreux produits industriels, il s'agit du juste milieu pratique. Cela résout les problèmes d'ajustement et de performance sans créer de nouveau verre de panneau.

Entièrement Affichage personnalisé

Un projet entièrement personnalisé peut modifier le contour du verre TFT, la zone active, la résolution, le rétroéclairage, le FPC et la construction mécanique.

Il peut fournir une géométrie exacte, mais il introduit également davantage d'outillage, d'engagements matériels, de validation et de risques liés au cycle de vie. Cette voie a généralement du sens lorsque la géométrie de l'affichage crée une réelle valeur produit et que le volume prévu justifie l'investissement.

Niveau de personnalisation	Principal avantage	Principale limitation	Utilisation typique
Sélection standard	Développement le plus rapide et risque le plus faible	Le produit doit accepter la géométrie et l'interface existantes	Prototypes précoces et boîtiers flexibles
Semi-personnalisé	Résout les problèmes d'intégration tout en conservant une plateforme TFT éprouvée	Certaines dimensions clés restent fixes	La plupart des projets industriels et OEM spécialisés
Entièrement personnalisé	Contrôle maximal de la zone active et de la géométrie du module	Charge plus élevée en outillage, MOQ, délais et qualification	Programmes stables à volume plus élevé avec des exigences uniques

Demandez au fournisseur de préciser exactement quelles couches sont standard et lesquelles sont spécifiques au projet.

Taille : définir plus que la diagonale

La taille diagonale est utile pour les catégories de produits, mais elle ne définit pas l'ajustement mécanique.

Deux affichages ayant la même diagonale peuvent avoir des rapports d'aspect, des zones actives, des dimensions extérieures, des largeurs de cadre et des positions de connecteur différents. L'un peut s'adapter au boîtier tandis que l'autre interfère avec un bossage ou place le FPC contre une courbure serrée.

Fournissez ou demandez ces dimensions :

• Zone active : la partie du display qui produit les pixels
• Zone de visualisation : l'ouverture à travers laquelle la zone active est visible
• Contour du module : les dimensions extérieures maximales du LCM complet
• Épaisseur totale, y compris les pics des composants
• Emplacement de la zone active à partir de références contrôlées
• Emplacement du connecteur et hauteur d'accouplement
• Position, direction et longueur de sortie du FPC
• Pattes de montage, trous et zones de support
• Zones interdites pour les composants et les courbures de câbles

AA et VA ne sont pas interchangeables

La zone active, communément appelée AA, est la zone contenant les pixels actifs.

La zone de visualisation, communément appelée VA, est l'ouverture visible définie par le cadre, le châssis ou l'impression de la façade. Elle est généralement légèrement plus grande que la zone active mais plus petite que le contour complet du module.

Confondre AA et VA peut produire des bordures visibles, des pixels coupés ou une fenêtre de protection qui expose des structures internes. Référencez les deux par rapport aux mêmes références mécaniques et incluez les tolérances.

Partager l'enveloppe maximale, pas seulement un contour cible

Si certaines dimensions peuvent varier, fournissez une enveloppe maximale autorisée et identifiez les obstructions fixes. Un fournisseur de modules d'affichage peut alors rechercher dans un groupe plus large de plateformes existantes.

Indiquez quelles dimensions sont fixées par l'outillage et lesquelles peuvent changer. Cela peut transformer une demande coûteuse de personnalisation complète en une solution semi-personnalisée à moindre risque.

Résolution et rapport d'aspect

La résolution doit découler du contenu et de la distance de visualisation, et non du nombre le plus élevé disponible.

Listez le plus petit texte, le nombre de commandes, le détail des graphiques, le contenu des images et la distance de visualisation prévue. Un instrument compact affichant quatre mesures n'a pas les mêmes besoins qu'un dispositif de diagnostic affichant des formes d'onde ou des images de caméra.

Une résolution plus élevée peut améliorer les détails fins, mais elle affecte également :

• La capacité du processeur et du graphisme
• La mémoire du framebuffer
• La bande passante de l'interface
• La charge de travail de développement de l'interface utilisateur
• Power consumption
• Pixel density under anti-glare cover treatment
• Availability of suitable TFT platforms

Match Aspect Ratio Before Finalizing the Enclosure

Common display shapes include 4:3, 16:9 and other wide, square, round or bar formats. Changing aspect ratio late can force a complete redesign of the user interface and front housing.

Prototype the interface at the actual physical size. A layout that looks comfortable on a desktop monitor may be difficult to operate on a small TFT.

Landscape and Portrait Require Separate Review

Rotating a display changes more than the drawing orientation. Preferred viewing direction, polarized-sunglasses behavior, cable routing, pixel order, graphics memory and touch coordinates may be affected.

Confirm portrait use before the panel and enclosure are frozen.

Brightness: Specify the Environment and Measurement Point

“High brightness” is not a complete requirement.

Describe whether the product operates indoors, near windows, in open shade or in direct sunlight. State the expected viewing distance, enclosure color, cover stack and available power.

Brightness is measured in candelas per square meter, commonly called nits. Clarify whether the requirement applies to:

• The bare TFT surface
• The display plus touch panel
• The outer surface of the completed cover-lens assembly

A touch sensor, adhesive and cover glass absorb and reflect part of the emitted light. The finished value may be lower than the panel rating.

Request the typical or minimum luminance, uniformity, measurement condition, dimming method and performance at high temperature.

Do not specify maximum brightness without reviewing heat and backlight life. In a sealed industrial enclosure, the thermal limit may matter more than the catalog value.

Viewing Angle and Image Stability

An HMI may be installed above eye level, below the operator or at the side of a machine. The display should be evaluated from those positions.

IPS TFT technology generally provides more stable contrast and color across wide viewing directions. TN can remain suitable when the viewing position is controlled and cost or availability favors it.

Define:

• Landscape or portrait installation
• Primary viewing direction
• Required horizontal and vertical viewing cone
• Critical colors and gray levels
• Use with polarized sunglasses
• Lighting at the installation point

Test the production interface, including small text, alarms and dark backgrounds. A colorful demonstration image can hide viewing-angle weaknesses.

Color Performance: Specify Only What the Product Uses

Many industrial products do not need cinema-grade color. They need alarms to remain distinguishable, brand colors to be consistent and graphs to be readable from unit to unit.

Useful requirements may include:

• Color depth
• White-point range
• Color-gamut target
• Unit-to-unit color tolerance
• Comportement gamma ou en niveaux de gris
• Color shift with viewing angle and temperature
• Whether calibration is required

Avoid demanding a wide gamut if the interface uses only simple status colors. It can narrow the panel choice without improving the operator’s task.

For medical imaging or measurement applications where color affects interpretation, define the applicable performance and validation process with a qualified engineer. A general-purpose TFT specification is not a substitute for system-level compliance.

Operating Environment

Temperature, humidity, sunlight, vibration and contamination influence material selection and test planning.

Provide:

• Minimum and maximum operating temperature
• Storage and transport temperature
• Required cold-start behavior
• Humidity and condensation conditions
• UV or direct-sun exposure
• Vibration and mechanical shock profile
• Dust, water and cleaning-fluid exposure
• Expected daily operating hours

Do not copy the widest available temperature range into the RFQ unless the equipment actually needs it. Wider requirements can reduce panel choice and increase cost.

Define what the image must do at the limits. At low temperature, pixel response can slow. At high temperature, brightness, contrast, adhesives and backlight life may be affected.

Touchscreen: Begin with the Operator

A custom touch display should be specified around the people and tools that operate it.

Projected capacitive touch, or PCAP, provides a durable glass front, clear optics and multi-touch capability. It may support defined gloves and wet conditions when the sensor, controller and firmware are engineered for the final stack.

Resistive touch responds to pressure and can normally be used with a finger, most gloves or a passive stylus. It remains useful for single-touch industrial interfaces and universal-glove operation.

Provide:

• Required touch technology
• Number of touch points
• Gesture requirements
• Actual glove type and thickness
• Finger, passive stylus or active stylus use
• Water and cleaning conditions
• Minimum touch-target size
• Required touch interface, typically I²C or USB for PCAP
• Operating-system and driver requirements

“Works with gloves” and “works when wet” are incomplete. Supply actual gloves and define whether water should be rejected or valid touch must continue.

Cover Lens: Treat It as an Engineered Part

The cover lens creates the visible face of the product. It also affects touch sensitivity, reflection, sealing and assembly tolerances.

A cover drawing should define:

• Material and thickness
• Outer dimensions and corner radius
• Holes, slots, notches and edge finish
• Viewing window
• Black mask and printed icons
• Logo and color requirements
• Transparent indicator windows
• Bonding and gasket areas
• Surface treatment
• Cosmetic acceptance limits

The printed border must hide adhesive, sensor traces and display structures without clipping the viewing area. Narrow glass features and holes should be reviewed for manufacturing and strength.

AR, AG and AF Solve Different Problems

AR treatment reduces mirror-like reflection.

AG treatment diffuses reflected light but may soften fine pixels when haze is excessive.

AF treatment reduces visible fingerprints and can improve cleanability.

Choose these treatments from the lighting, resolution and maintenance requirements. Verify chemical resistance against the actual cleaning agents.

Optical Bonding or Perimeter Bonding?

Perimeter bonding attaches the touch panel or cover lens around its edge, leaving an air gap over the TFT. It is economical and can simplify rework.

Optical bonding fills the gap with transparent adhesive. It can reduce internal reflections, improve perceived contrast and remove the air cavity in which condensation might form.

Optical bonding may be justified for outdoor equipment, strong ambient light, premium optical appearance or mechanically integrated front assemblies.

It also affects cost, process yield and repair strategy. A bonded stack is normally serviced as a complete assembly rather than as separate layers.

Define bubble, particle, alignment and cosmetic acceptance criteria before approving the bonded sample.

Interface: Start with the Host Processor

Select the display interface from the host’s native capability, graphics workload and cable environment.

Common small-TFT interfaces include:

• SPI for low pin count and modest update requirements
• MCU or 8080 parallel interface for direct writes and higher throughput
• RGB for continuous pixel streaming
• MIPI DSI for high bandwidth with fewer differential lanes
• LVDS or eDP for selected larger or higher-bandwidth displays

HDMI, USB or serial HMI solutions may be provided through a driver or conversion board when the host does not expose the panel’s native interface.

State:

• Processor part number and operating system
• Native display peripheral
• Resolution, color depth and frame-rate target
• Full-screen or partial-update behavior
• Logic voltages
• Timing requirements
• Initialization commands
• Power-up and power-down sequence
• Backlight control and dimming
• Cable length and EMC environment

The connector name is not an interface specification. Pinout, timing, voltage and initialization must all match.

FPC and Connector Customization

A custom FPC can solve a mechanical conflict without changing the TFT glass.

Define:

• Exit side and direction
• FPC length and bend location
• Minimum dynamic or static bend radius
• Stiffener dimensions
• Connector manufacturer and part number
• Contact side and pin assignment
• Mating height
• Required shielding or ground features
• Assembly and service access

Do not fold the FPC across components or force it against a sharp housing edge. Add strain relief where vibration or repeated service movement is expected.

If the connector position is fixed on the host PCB, provide a 3D envelope or assembly drawing rather than only a two-dimensional panel outline.

Mechanical Integration and Tolerance Stack

Display fit should be assessed across the complete assembly, not one nominal drawing.

Review tolerances from the TFT active area through the frame, touch sensor, cover printing, adhesive, bracket and enclosure. A series of acceptable individual tolerances can still place the visible image too close to one edge.

Define mechanical datums and inspection points. Identify surfaces that can support the module and areas that must remain free of pressure.

Avoid point loading the TFT glass. Uneven screw torque, warped bezels and over-compressed foam can create light leakage, pressure marks, mura or glass damage.

Account for thermal expansion where the cover lens, plastic housing and metal frame use different materials.

Separate Requirements from Preferences

An RFQ becomes easier to solve when every line has a priority.

Use three labels:

• Fixed: cannot change because of safety, tooling, compliance or host architecture
• Preferred: valuable but open to a justified alternative
• Flexible: supplier may select from existing platforms

Example:

Paramètre	Value	Priority	Reason
Maximum module width	72.0 mm	Fixed	Existing enclosure tool
Résolution	800 × 480 preferred	Preferred	Current UI layout
Connector position	Rear, right side	Flexible	PCB routing not frozen
Cover logo color	Brand reference sample	Fixed	Product identity
Display interface	RGB or LVDS	Flexible	Host supports both

This format gives the manufacturer room to find a stable platform without compromising product-critical items.

Build a Complete RFQ Package

A strong custom TFT LCD RFQ includes four groups of information.

Product and Commercial Context

• Application and end market
• Prototype, pilot and annual quantities
• Target sample date
• Expected production start
• Required supply and service period
• Target market or compliance constraints

Optical and Environmental Requirements

• Size, resolution and orientation
• Brightness measurement point
• Viewing direction and lighting
• Color requirements
• Operating and storage temperature
• Humidity, shock, vibration and UV exposure

Electrical Requirements

• Host processor
• Display and touch interfaces
• Voltages and power budget
• Frame-rate and update behavior
• Connector and pinout
• Software and driver environment

Mechanical and Cosmetic Requirements

• 2D drawing with tolerances
• 3D file or enclosure envelope where available
• FPC and connector position
• Touch and cover construction
• Printing and color references
• Bonding method
• Cosmetic inspection criteria

If information is unknown, say so. An explicit open item is safer than an assumed requirement.

Prototype Strategy: Answer One Risk at a Time

Trying to perfect image quality, mechanics, touch tuning and cosmetics in the first bonded sample can make failures expensive and difficult to diagnose.

A staged program is usually easier to control.

Stage 1: Electrical Evaluation

Use a standard or near-standard display to confirm initialization, timing, color order, image orientation, frame rate, sleep, wake and backlight control on the intended host.

Stage 2: Mechanical Sample

Confirm outline, active-area location, connector access, FPC routing and mounting. A non-cosmetic cover sample can validate fit before final printing.

Stage 3: Optical and Touch Stack

Add the production-intent touch panel, cover thickness, adhesive and surface treatment. Tune PCAP in the real enclosure.

Stage 4: Cosmetic Sample

Approve printing, color, logo, window alignment, particles, scratches, bonding bubbles and edge appearance against written standards.

Stage 5: Pilot Build

Run the assembly process at limited quantity. Record yield, work instructions, test coverage, packaging and any rework before mass production.

This sequence is not mandatory for every project, but it helps isolate problems before the most expensive configuration is built.

Testing and Acceptance Criteria

“Sample approved” should mean more than the display powers on.

Create measurable criteria for:

• Active-area and module dimensions
• Connector, FPC and mounting fit
• Pixel defects
• Luminance and uniformity
• Color and viewing performance
• Touch accuracy and edge response
• Glove and water behavior
• Bonding alignment, bubbles and particles
• Backlight dimming
• Power consumption
• Startup and recovery
• Operating-temperature behavior
• Vibration or shock response where required

The finished equipment manufacturer remains responsible for system-level compliance. Module testing supports that work but does not certify the complete medical, automotive or industrial product.

Use a Golden Sample Carefully

An approved golden sample can preserve visual and cosmetic expectations that drawings do not fully capture.

Store it under controlled conditions and link it to a specific drawing, BOM, firmware and approval date. A golden sample without revision control can create disagreement later.

Change Control Before Mass Production

Freeze the approved configuration before issuing a production order.

The controlled package may include:

• Module drawing and revision
• Bill of materials or controlled critical components
• Display initialization code
• Touch-controller firmware
• Cover-lens artwork and color reference
• Bonding stack
• Cosmetic standard
• Test procedure and acceptance limits
• Packaging specification
• Approved sample record

Define how supplier changes will be communicated and which changes require customer approval or requalification.

Sample and Production Timing

Development time depends on what changes.

Selecting an existing display may take only technical review and sample logistics. Custom FPC, cover glass, touch sensors, backlights or driver boards add drawing, tooling and validation steps. Fully custom TFT glass requires a substantially different commercial and technical commitment.

QIHAN currently publishes these general reference periods:

• LCM drawing: approximately 2–7 days
• LCM sample: approximately 3–6 weeks
• Mass production: approximately 4–12 weeks

These are not universal promises. Actual timing depends on the module platform, tooling, material availability, customization depth, sample revisions, order quantity and required testing. Confirm the schedule in the quotation for the specific project.

What Commonly Delays a Custom Display Project?

Frequent causes include:

• Enclosure tooling frozen before the display drawing
• Unconfirmed processor or interface
• Cover artwork without controlled color references
• Glove or wet-touch requirements added after tuning
• Brightness specified at the wrong optical surface
• Mechanical changes after optical bonding
• Missing acceptance criteria
• Forecast or MOQ discussed only after engineering begins

Most of these delays can be prevented by a complete initial specification and staged approval.

What to Expect from a TFT Display OEM Partner

A useful supplier does more than quote the closest diagonal size.

Before design freeze, expect clear discussion of:

• Which requirements match a standard platform
• Which changes require tooling
• Which tolerances are critical
• Which performance is proven and which requires validation
• What the sample will and will not represent
• Which test data applies to the exact construction
• Who controls firmware and drawings
• How changes and end-of-life events are handled

If a requirement cannot be confirmed, it should remain an open item rather than being converted into a marketing claim.

How QIHAN Supports Custom TFT LCD Projects

QIHAN is a manufacturer and supplier of small and medium-sized TFT LCD modules from 0.96 to 15.6 inches for industrial, medical, automotive, HMI and embedded applications.

QIHAN’s published OEM and ODM capabilities include project-based customization of display size, resolution, brightness, interface, backlight, touch panel, cover lens, FPC, optical bonding, PCB and mechanical structure.

The company also publishes production capabilities covering TFT processing, backlight assembly, capacitive-touch assembly and TFT-to-CTP optical bonding.

Available dimensions, performance, MOQ, tooling and development time depend on the selected TFT platform and the parts that become custom. They should be confirmed in the project drawing and quotation.

Questions fréquemment posées

What information should I send to a TFT LCD manufacturer?

Send the application, visible area, maximum outline, resolution, brightness, operating environment, host processor, interface, touch requirement, cover-lens drawing, expected quantity and target schedule. Mark fixed and flexible requirements.

Do I need a fully custom TFT LCD?

Often, no. A standard panel with a custom FPC, backlight, touch panel, cover lens or interface board may solve the integration problem with lower tooling and qualification risk.

Can the display size be customized?

The external module, cover lens and integration features can often be adapted. A unique active area or TFT glass size is a deeper customization that depends on tooling, technical feasibility and volume.

Can QIHAN customize the display interface?

QIHAN supports project-based interface and FPC customization as well as driver-board and interface-conversion solutions. Compatibility must be checked against the host processor, timing and software environment.

How long does a custom TFT LCD sample take?

QIHAN publishes approximately 3–6 weeks as a general LCM sample reference. A standard sample may be quicker, while a complex touch, cover, bonding or full-custom project may require more time. Use the project quotation as the controlling schedule.

What is the MOQ for a custom TFT display?

There is no single MOQ. It depends on whether the project uses a standard module, custom FPC, dedicated backlight, touch sensor, cover lens or new TFT glass. Share prototype, pilot and annual-volume estimates early.

Can a custom display be used in automotive or medical equipment?

It may be designed for those applications, but the required qualification, documentation and system compliance must be defined for the specific product and market. A general custom-module description is not proof of certification.

Who is responsible for final product testing?

The display supplier validates the agreed module requirements. The equipment manufacturer is responsible for verifying the complete product, including EMC, safety, environmental performance and applicable regulatory compliance.

Define the Product Before Asking the Display to Fit It

A custom TFT LCD display project works best when the product team and supplier solve the constraints together.

Freeze the visible area before the bezel. Match resolution to real content. State where brightness is measured. Select touch from the operator’s hands. Treat the cover lens as an optical and mechanical component. Match the interface to the host, and validate risk in stages before approving mass production.

QIHAN can review your mechanical envelope, host interface, lighting, touch, cover and production requirements to identify whether a standard, semi-custom or fully customized LCD module is appropriate.

Send your custom TFT LCD specifications to QIHAN.