Editor's Note: Among the many solutions for endoscopic handle focusing and zooming, DC coreless geared motors require encoders and servo control, keeping cost and complexity high; ultrasonic motors offer ideal performance but have no off-the-shelf mass-produced models to choose from. The recommended Ø4.5mm reduction leadscrew stepper motor below integrates the stepper, reduction gear, and leadscrew output into one unit, delivering 3.5N thrust—achieving micron-level positioning in open-loop and featuring built-in power-off self-locking. Its manufacturing difficulty is extremely high, with few competitors in the industry. Already adopted by multiple companies, we'd like to share this with fellow practitioners.
LPD4R5SG-005 Product Introduction
Ø4.5 Reduction Leadscrew Stepper Motor · Dedicated for Endoscopic Handle Focusing & Zooming
Ø4.5mm stepper + 1/20.25 planetary reduction + leadscrew—a rare miniature linear stepper module in the industry.
Key Parameters
| Item | Spec |
|---|---|
| Geared motor outer diameter | Ø4.5 mm |
| Mass | 2.6 g |
| Rated voltage | 5.0 VDC (3.0–5.0 V usable) |
| Drive | 2-phase bipolar stepper, constant-voltage drive |
| Step angle | 22.5° (16 steps/rev) |
| Reduction ratio | 1/20.25 (planetary gearbox) |
| Linear displacement per step | 0.0033 mm/step (calculated) |
| Thrust (rated operating point) | 350 gf ≈ 3.43 N (@5V / 2400 pps, motor-down orientation) |
| Nut travel speed | 17.4 mm/s (same condition, load 350 gf) |
| Noise | ≤ 50 dB(A) (after 300k cycles) |
| Life | 300k reciprocating cycles, thrust degradation ≤ 20% |
| Operating temperature | -20 ~ +55°C |
| Phase resistance | 14Ω ±10% @25°C |
Why It Fits Endoscopic Focus/Zoom
✅ Compact size
Ø4.5mm motor + planetary reduction + leadscrew integrated—shortens development lead time and simplifies drive control.
✅ 0.0033 mm/step, high resolution
For a lens group travel of 2–5 mm, open-loop alone covers hundreds to thousands of focal points—no extra encoder needed for fine focus.
✅ 3.4N thrust (@2400 pps) + stepper self-locking
Lens load is typically 50–150g, so thrust is more than sufficient. Leveraging the stepper's inherent detent torque, amplified through the gearbox, it achieves power-off self-locking.
✅ 5V low voltage + 2-phase bipolar
Drivable with a single small-package IC from Allegro / TI—easy to place and route even in tight spaces.
✅ 2.6g—barely noticeable in handle balance
Application Scenarios
- 4K/3D laparoscopic handle electronic focus/zoom
- Surgical robot slave-side focus/zoom
- Industrial endoscope focus/zoom
- Smartphone camera module lift mechanisms
Market Validation
Multiple endoscopic OEMs have already adopted this product in handle focus/zoom solutions, validating its engineering feasibility in small-size, high-resolution, open-loop self-locking scenarios.
Manufacturing Difficulty (Why Few Competitors)
Integrating "Ø4.5mm motor + planetary reduction + leadscrew output" into one unit faces three hurdles:
- Ø4.5 stator lamination stamping & winding—tooth width is only fractions of a millimeter; the winding needle barely fits. Yield is the primary bottleneck.
- Planetary gears with extremely small module—mesh precision of sun gear / internal ring gear directly determines noise and the 300k-cycle life.
- Leadscrew coaxiality ≤ 0.11mm—motor shaft → gearbox → leadscrew triple-section coaxiality requires extremely high fixture and assembly stability.
While the product looks tiny, it sits at the intersection of three process disciplines: micro-motor + precision gears + precision leadscrew—with considerable technical barriers.
Product Images (reference)
