Toshiba CF3R Printhead 20mm Drop Waveform Adjustment Guide
Toshiba CF3R High-Drop (20mm) Printing — Practical Guide
The Toshiba CF3R printhead, equipped with high firing pressure and an internal circulation system, breaks through the traditional 5 mm printing limit, enabling 20 mm high-drop printing. However, in such a high-drop environment, ink droplets are easily affected by air resistance and gravity, leading to velocity loss and offset, which can cause ink accumulation, banding, and color inconsistency. To solve these precision challenges, it is necessary to systematically optimize waveform parameters, ink characteristics, and hardware systems with dynamic compensation.
I. Core Waveform Parameter Adjustment Standards
(1) Three Fundamental Pulse Elements (20 mm Drop Adaptation)
| Parameter | Standard Printing Setting | Optimized Setting for 20 mm Drop | Adjustment Logic |
|---|---|---|---|
| Pulse Width | 1.8–2.2 μs | 2.3–2.6 μs (+0.2 μs for high-viscosity ink) | Extend pulse width to enhance jetting energy and offset velocity loss caused by the drop. |
| Peak Voltage | 24–28 V | 29–32 V (≤34 V safe limit) | Increase voltage to compensate energy loss and ensure stable droplet landing. |
| Rising Slope | 35–40 V/μs | 45–50 V/μs | Reduce jetting delay to maintain consistent initial droplet velocity. |
Ideal Condition: Two-point droplet speed ≤0.5 m/s (recommended 5.5–6.0 m/s). Note: Peak voltage above 34 V may cause nozzle wear; pulse width above 2.8 μs may generate satellite droplets.
(2) Dynamic Compensation Strategy for Drop Height Segments
To handle various height differences, waveform parameters must be independently set by height zones. Using CF3R’s fine-tuning feature for single-nozzle adjustment enables precise compensation.
| Drop Zone | Pulse Parameter Adjustment | Gray Scale Adaptation (CF3R 6 Levels) | Application Scenario |
|---|---|---|---|
| 0–5 mm (Low Zone) | Pulse width −0.1 μs, Voltage −1 V | Prefer 3–8 pL small droplets to reduce splashing | Base details of raised structure |
| 5–15 mm (Mid Zone) | Baseline (2.4 μs + 30 V) | 8–15 pL medium droplets for color uniformity | Main pattern area |
| 15–20 mm (High Zone) | Pulse width +0.2 μs, Voltage +2 V, add pre-pulse | 15–20 pL large droplets to compensate layer thickness | Top fill printing |
Operational Key Points: Establish a “Drop Height–Waveform Parameter Mapping Table” in the device for real-time adjustments. For high-zone printing, add an extra 1.2 μs pre-pulse to activate chamber pressure and prevent large droplet delay.
(3) Ink Characteristic Adaptation (Mandatory Step)
Different inks require waveform optimization based on their physical characteristics to ensure stable jetting and consistent grayscale control.
| Ink Type | Waveform Adjustment Focus | Auxiliary Parameter Coordination |
|---|---|---|
| UV-Curing Ink | High surface tension (30–35 mN/m): extend fall time by 1 μs to avoid splashing or splitting | Increase inner circulation speed to ≥30 ml/min to prevent curing blockage |
| High-Viscosity Ink | Add +0.3 μs pulse width, +3 V voltage to compensate low fluidity | Maintain ink temperature at 35–40 °C to reduce viscosity |
| Oil-Based Ink | Reduce peak voltage by 1–2 V to minimize misting | Maintain humidity at 40–50% to balance evaporation rate |
II. Equipment Coordination and Environmental Control
(1) Hardware Synchronization
Printhead Height Calibration: Use 20 mm drop’s highest point as reference; initial height = 25 mm (5 mm safety margin).
Cooling System Optimization: For high-frequency printing (≤8 kHz, below CF3R’s 9.2 kHz limit), increase water cooling flow to 8 L/min and keep water temperature at 22 ± 2 °C to prevent piezoelectric thermal decay.
Negative Pressure System: Low zone: −3.5 mbar (anti-leakage); High zone: −5.0 mbar (enhance ink supply pressure).
(2) Environmental and Consumable Control
Temperature: 20–25 °C; air flow <0.3 m/s to avoid droplet deviation.
Ink Filtration: Use a 5 μm filter with internal circulation to prevent pigment sedimentation and waveform instability.
Regular Maintenance: Perform “waveform calibration + nozzle cleaning” every hour of printing to maintain trajectory accuracy. Recalibrate when deviation > 0.1 mm.
III. Debugging Process and Troubleshooting
(1) Standard Debugging Steps (2–3 Hours)
Baseline Setup: Set waveform to 2.4 μs + 30 V and print test patterns to confirm 6-level grayscale output.
Drop Calibration: Adjust for each zone (0–20 mm in 5 mm increments) to calibrate waveform parameters.
Dynamic Testing: Print gradient images and inspect transitions under magnification for banding or blur.
Stability Verification: Conduct 30-minute continuous printing; monitor printhead temperature (≤40 °C) and velocity decay (≤5%).
(2) Common Issues and Solutions
| Issue | Waveform-Related Cause | Solution |
|---|---|---|
| Blurred ink dots in high zone | Insufficient pulse energy, droplet velocity < 5 m/s | +1 V voltage, +0.1 μs pulse width |
| Ink buildup in low zone | Excessive speed (> 6.5 m/s) | −2 V voltage, extend fall time by 1.0 μs |
| Grayscale banding across height | Delay in parameter switching | Shorten waveform switching interval (every 2 mm per group) |
| Precision decline during long printing | Printhead heating causes waveform drift | Reduce frequency to 7 kHz, increase cooling flow to 10 L/min |
IV. Safety and Maintenance Guidelines
(1) Never print without droplet monitoring. At a 20 mm drop, even a 0.1 μs / 1 V deviation can cause serious print defects.
(2) Do not exceed 32 V when using high-viscosity ink, to prevent piezoelectric overload.
(3) Always recalibrate waveform after changing inks to match surface tension and viscosity differences.
(4) Nozzle micro-adjustment is mandatory. At 20 mm height, nozzle inconsistency is magnified; offset across 1278 nozzles must be ≤0.05 mm.
Summary
The core of CF3R high-drop printing lies in the synergy between waveform, ink, and hardware. Through precise pulse adjustment, segmented dynamic compensation, and ink property optimization, stable jetting, accurate deposition, and high grayscale performance can be achieved even at a 20 mm drop. This ensures reliable results across industrial-grade UV, oil-based, and high-viscosity printing applications.