Advancing E-Paper: The Modos Color Monitor

The team at Modos is once again leveraging the "wisdom of the crowd" to push the boundaries of electronic paper technology. After the success of their initial foray into open-source hardware, the two-person startup is introducing a more ambitious product.

From Dev Kit to Consumer Hardware

Last autumn, Modos captured the attention of the tech community with their Paper Monitor and Dev Kit. This open-source project was a milestone in e-paper performance, achieving a record-breaking refresh rate of $75\text{ Hz}$ . The campaign was a resounding success, securing nearly twice its original funding target of US $110,000.

Building on that momentum, cofounders Alexander Soto and Wenting Zhang have launched a new crowdfunding campaign on Crowd Supply for the Modos Flow.

The Modos Flow: Key Specifications

The Flow is a significant leap forward from the Dev Kit, transitioning from a developer tool to a fully integrated monitor.

Display Size: 13.3 inches
Color Support: Yes
Native Resolution: 3,200 x 2,400
Refresh Rate: $60\text{ Hz}$
Input: Touch-enabled
Connectivity: Single USB Type-C port (designed for PC/Laptop integration)

The Engineering Behind the "Enchanter"

The secret to the Flow's increased resolution and performance is a new open-source display controller dubbed the Enchanter.

"The new board has a larger, newer FPGA [field-programmable gate array], has double the DDR3 memory bandwidth, and a power supply that delivers higher currents for the more power-hungry screen," explains Wenting Zhang.

Hardware Architecture

To achieve higher resolutions while maintaining an open-source ethos, Modos utilized the Chrontel CH7516 DisplayPort-to-LVDS converter.

Why this chip?

~~DisplayPort 1.0~~ $\rightarrow$ DisplayPort 1.1: The CH7516 supports the 1.1 standard, which is essential for the higher pixel density.
Open Documentation: Modos refuses to use components gated behind Non-Disclosure Agreements (NDAs). The CH7516 provided the necessary specs without legal restrictions.

Signal Flow Diagram

Addressing the "Latency Myth"

A frequent criticism of e-paper is that high refresh rates are meaningless if the physical pixels respond slowly. Modos addresses this by analyzing the physics of pixel transitions.

In standard LCD testing, response time is measured as the duration a pixel takes to move from 10% to 90% of its target brightness: $\text{Response Time} = t_{90\%} - t_{10\%}$

Response Time Comparison

Display Type	Response Time (Approx.)	Note
Older E Ink (Glider)	$\sim 100\text{ ms}$	Previous generation
Modos Flow (Enchanter)	$\sim 50\text{ ms}$	Significant improvement
1st Gen iPad (IPS)	$\sim 30\text{ ms}$	Industry benchmark

While $50\text{ ms}$ is still slower than a traditional IPS panel, Zhang argues that perceived latency is not about the completion of the pixel change, but the initiation of it. By eliminating buffering within the controller and maintaining a high frame rate, Modos minimizes the lag felt by the user when moving a cursor.

Project Roadmap & Philosophy

Modos remains committed to a transparent development cycle. Their goals for the Flow include:

Develop Enchanter controller board
Integrate DisplayPort 1.1 support
Implement touch input
Complete Crowd Supply funding phase
Mass production and shipping

Technical Implementation Note

For those interested in the logic of the controller, the process can be simplified as follows:

// Conceptual logic for the Enchanter Controller
if (input_signal == DISPLAYPORT_1_1) {
    increase_bandwidth(DDR3_DOUBLE);
    set_refresh_rate(60);
    bypass_buffer(); // Minimize latency
}

By combining open-source hardware with strategic component selection, Modos is attempting to make e-paper a viable alternative for professional computing environments.