Key Takeaways
- A novel flip‑disc display (named PAR) uses a CNC‑driven tool head instead of per‑pixel actuators.
- The panel consists of 37 × 18 = 666 square discs, each black on one side and blue on the other.
- Positioning is achieved with a color sensor and a LIDAR rangefinder, giving ±0.1 mm accuracy.
- Refresh speed averages 1 frame ≈ 12 seconds (≈ 55 ms per disc) – slower than magnetic systems but mechanically simple.
- Users can upload custom graphics via a web interface; the CNC controller translates the bitmap into a sequence of flips.
Introduction: Rethinking Flip‑Disc Actuation
Traditional flip‑disc (or “flap‑board”) displays rely on an electromagnetic coil or piezo actuator behind every individual disc. While this architecture delivers sub‑millisecond switching, the sheer number of drivers (often thousands) drives up cost, wiring complexity, and power consumption.
Engineer Zimm proposes a radically different approach: replace the per‑pixel hardware with a single CNC milling head that physically flips each disc in turn. The concept mirrors a plotter that “writes” an image by moving a stylus across a sheet, but here the stylus pushes a disc to expose its opposite face.
How PAR Works
Mechanical Layout
- Panel size: 370 mm × 180 mm (≈ 1.2 ft × 0.6 ft).
- Disc count: 37 columns × 18 rows = 666 discs, each 10 mm × 10 mm × 2 mm thick.
- Actuator: Standard 3‑axis CNC router (NEMA‑23 stepper motors, 2 µm micro‑stepping).
Sensing & Control
| Sensor | Role | Spec |
|---|---|---|
| Color sensor (TCS34725) | Detects current disc side (black vs. blue) | 16‑bit RGB, ±0.5 % accuracy |
| LIDAR (VL53L0X) | Measures disc height to determine flip depth | 4 cm range, 1 mm resolution |
| Controller | Generates G‑code from bitmap | Raspberry Pi 4, 4 GB RAM, 1 GHz CPU |
The CNC head follows a raster scan pattern. At each coordinate, the color sensor confirms the disc’s orientation. If the disc does not match the target bitmap, the head lowers until the LIDAR registers contact, then pushes the disc ≈ 1.2 mm to flip it. The process repeats until the entire frame is rendered.
Performance
- Average flip time: 55 ms per disc (including sensor readout).
- Full‑frame refresh: ~12 s for 666 discs.
- Power draw: 12 V × 2 A (≈ 24 W) for the CNC motors; negligible for sensors.
While the refresh rate is far slower than magnetic flip‑discs (which can achieve 30 fps), the system eliminates 666 individual coils, reducing component count by > 99 %.
Comparison: CNC‑Driven vs. Magnetic Flip‑Disc
| Feature | CNC‑Driven (PAR) | Magnetic Flip‑Disc |
|---|---|---|
| Actuators | Single CNC head (1 motor set) | One coil per disc (≈ 666 coils) |
| Refresh Rate | 0.08 fps (≈ 12 s per frame) | 30 fps (typical) |
| Power Consumption | ~24 W total | 150–300 W (depends on coil count) |
| Cost (Bill of Materials) | ≈ $350 (CNC kit + sensors) | ≈ $2,500 (coils, drivers, wiring) |
| Reliability | Low moving‑part wear (steel‑on‑plastic) | High coil failure rate over time |
| Scalability | Easy to expand panel size (just longer travel) | Exponential cost & wiring growth |
User Interaction
The PAR web portal (https://par.zimmzimm.com/upload) lets anyone drag‑and‑drop PNG or SVG files. The server rasterizes the image to a 37 × 18 binary matrix, then streams G‑code to the CNC controller over Wi‑Fi. Users can also program simple animations by uploading a sequence of frames; the controller queues them automatically.
Applications & Limitations
- Art installations where slow, deliberate updates are acceptable.
- Educational demos illustrating CNC precision, sensor integration, and low‑cost display tech.
- Prototype signage in environments where power is scarce.
Limitations include the modest refresh speed, audible motor noise, and the need for a stable, flat surface to prevent disc mis‑alignment.
Bottom Line
Zimm’s PAR flip‑disc display demonstrates that a single CNC machine can replace thousands of individual actuators, trading speed for dramatic reductions in hardware complexity, power draw, and cost. Although it cannot compete with high‑speed magnetic boards, its elegance lies in leveraging existing CNC technology to produce a functional, programmable visual display with under a hundred dollars of parts. For makers, educators, and low‑budget installations, PAR offers a compelling proof‑of‑concept that “slow and steady” can still make a striking visual impact.
