February 23, 2024


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Adobe Scientist cuts the dash with the changing LCD dress

Adobe Scientist cuts the dash with the changing LCD dress

Adobe Research Scientist [Christine Dierk] He showed off an interesting new project at the Adobe Max conference: The Primrose Project, a dress covered in a series of liquid crystal panels that can react to movement, changing the design of the dress. Now, Adobe has released a A paper explaining some of the technical details of the process.

This paper is from the User Interface and Software (UIST) conference in 2022, so the examples it uses are older: it discusses a canvas and a handbag. The dress uses the same technique, with a globe drape instead of a frame. If you cannot access the version from UIST, [Dierk] Has a free version here.

The dress uses polymer dispersion liquid crystal (PDLC) panels from the eponymous Shanghai HO HO Industry Co., designed for use in windows and doors for privacy. It uses tin iridium oxide coated PET film which is opaque by default but becomes transparent when a potential difference is applied across the material.

These boards are formed into hexagons, then connected together using flexible PCBs in a daisy chain. Interestingly, [Dierk] I found that the smaller the panels, the less effort required to operate them. For their canvas example, they lowered the voltage to safer levels -15V to 15V to power both states, which is safer for a wearable device.

The panels are also not completely transparent when turned on: the paper describes them as having a “soft ivory” appearance when on top of a reflective material. Grayscale can also be created using pulse coding modulation (PCM) to change the transparency of the panel. By driving the panels at 3.2 kHz, 64 shades of gray were created.

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The main controller is a custom PCB with Teenager 4.1 And a BlueFruit LE SPI module. Power comes from two 14.8V LiPo batteries, with inverters to power the chips and switching modules so the teen can switch the -15 and +15V levels of the panels directly from each battery.

The array consists of modules, each containing four boards connected to a control PCB, which contains several ADG1414 Analog Signal Device (ASD) chips. It receives these signals from the bus with switching registers to switch the panels individually.

But intelligently [Dierk] The bus that connects the modules together is used to provide both power and the bus signal that controls the boards, using the built-in -15 and +15 volt levels of a 50 Hz square wave to create the bus signal and power the boards at the same time. This is an elegant hack that reduces the complexity of modules significantly.

The Teensy 4.1 controls the entire system and can use its IMU to sense movement and change the pattern accordingly. You can’t see the system’s electronics in the dress video, but they claim the fabric example only took 0.58 watts to run, so the dress probably only needed a few watts.

It’s a great build (and a rather cute dress), and has a lot of potential. What are you going to do with this?