Change Notice: We opened the Amazon Glow and learned how Amazon turned a projector into a touchscreen

Chris Li

In the fall of 2021, Amazon announced the Glow, a new product that facilitates communication and interaction between children and remote family members. All this is achieved with a combination of screens, projection, and cameras. 

At first it was a Day 1 product, which is their way of gauging the market interest and reactions. This is a clever strategy that allows them to limit the initial production run while also having time to improve the experience of a new product type. With enough positive feedback, they opened it up for sale to the general public earlier this year.

Amazon Glow courtesy of Amazon.com.

We chose this product because we were interested in the technology behind the novel interactions in this projector-based system. How did Amazon cram all the technology in there for the relatively inexpensive price of $299? How do they detect touches on the projected images?  We opened up and explored the Glow to try and find out.

 

Overview of the Amazon Glow

Weighing in at just over 3.5 lbs, the Amazon Glow is a tall device at just over 14” in height. The plastic housing encases a touchscreen display, front camera, big speakers and several large buttons much like a typical tablet or echo product would. 

However, the big changes occur near the top where an outcropping holds the projector head and overhead cameras. To balance the weight of that protrusion, the design team has also incorporated a counter weight in the base giving it a bit of a Z-shape. The only port on this product is a barrel jack for 12V DC power. Because this is a device for children and designed to sit in the home, Amazon also includes a physical privacy shutter which simultaneously closes both the front and downward facing cameras.

 

Tearing down the Amazon Glow

Because the device needs to be indestructible, given its target audience of young children, I needed some extra help to open it. Before the live teardown, I peeled back the soft textured feet to expose some screws and also took the heat gun to the plastic speaker grill panel to loosen the hot-melt glue there. 

Taking out two screws beneath the speaker grill and some screws holding an accessory PCB in place, I could finally start to pry apart the two halves. Because of how physically large the product is, the hooks and snaps were not particularly easy to separate and they made an awful cracking sound just before the two halves came free. 

Once I had the product open, Will took us on a virtual tour of the inside using the Instrumental app.

Front half of the Amazon Glow.

 

PCBA and Flex Cables

One of the first things he noticed about the system is the 15 different connectors! In addition to the typical display, touch, and speaker connectors a laptop or tablet might have, this device also has connections for the projector and IR touch system as well as separate boards for the microphones and IR LEDs.

The main PCBA for the Amazon Glow.

With so many connectors, it can be hard to keep them all straight in the factory and it is critical that each connection be made and seated well. On this board, we saw evidence of sharpie marks on both the connector and the cable which we think were done as a manual verification that the cables were inserted properly in the factory. A few of the connectors also had kapton tape over them and after polling the audience we all agreed that this was likely a reliability fix to prevent those connections from coming loose.

Close-up of the lower connectors. Note the sharpie lines, the missing USB connector outline, and the helpful note to insert the flexes from the bottom side.

Another interesting thing about this board is the number of artifacts left from development. There is a random dome switch on the lower left side of the board – possibly for a manual reset – though this switch is hidden from customers. There are also unstuffed connector pads for a USB connection as well as a TOF or Time of Flight sensor. The TOF sensor was one of the ideas a few audience members suggested as a way that helps Amazon track touch events, but turns out it wasn’t necessary after all.

 

Optical module

Four screws secured the cast magnesium bracket holding the projector, RGB and IR cameras. Because the cameras are integral to measuring touch over the projected images, each of these modules is carefully positioned for consistency and likely calibrated at the factory. Looking closely we see that both cameras have pin and slot locators and it helps that they are located to the same surface. We also turned the module around and saw that the projector is screwed into place but has some springs which might allow for careful tuning of the image to get it to focus just right.

Optical module of the Amazon Glow.

Despite all the lengths that Amazon engineers went to guarantee repeatable positioning, there were also some manually placed items. The flex routing for each of the different sensors is unique and as Will pointed out, the cables of these sensitive instruments are bent to fit through and around the bracket. Additionally, several pieces of foam are added around the module to prevent leakage into other parts of the optical system. These pieces of foam are typically added by hand in the factory leading to some variability between devices. Instrumental customers often find issues with these gaskets during development and into mass production especially when they can be correlated with test data.

Just underneath the optical bracket we found the physical shutter mechanism which cleverly translates a vertical motion of the switch into horizontal motion. This secondary part not only serves as the shutter for the upper camera, but also moves another shutter in a downward motion to cover the main camera.

Physical slider mechanism on the left translating the motion to two separate shutters for the Glow’s cameras.

While playing with the Glow before taking it apart, we noticed that the main touch sensing seemed to be done using the camera system, but there must have been a reason the IR camera was also added. We looked for a source of IR and found it on another module near the base of the product.

 

IR Touch

The last item we covered was the small module at the base of the product connected by a small ribbon cable. This pair of IR LEDs (as labeled on the PCBA) likely provide a stereo field of view to flood the base of the tabletop. A child’s finger tap on the table would interrupt the beam enabling the IR camera to triangulate where the touch occurred. Working in concert with the RGB Camera, this could help provide additional information about when touches occur during games or making sure drawings are more accurate.

IR LED board from the base of the Amazon Glow.

While looking at the images on the platform, Will drew some lines showing the center of the emitter is aimed at the notch in the clear diffuser. This spreads the beam out across the surface of the projected area. The different components of this IR module appear to require some level of precision because each of the components is actually glued in place after they are assembled.

Close up of the emitters and the diffusers with a line drawn to indicate alignment and glue holding the parts in place.

 

Creating a new product category

As a former Amazonian, I am continually impressed by how Amazon continues to create new product categories. While it seemed like they were going to great lengths to put Alexa into everything, the Amazon Glow shows that new product categories are possible when the confluence of hardware and software merge to solve different problems for different users. Having worked on an infrared Kindle Touch back in the day, it was also fun for me to see how IR touch was being adapted into a totally new form factor. I look forward to seeing what other Day 1 products Amazon comes up with. If you enjoyed this teardown, let us know what you’d like us to open up next! 

For access to the teardown library with the Amazon Glow and all of the other devices from the Change Notice Unsnapped series, contact us at communications@instrumental.com.

Chris Li is a former Amazon Product Design Engineering Manager and teardown lead for Instrumental. He brought multiple generations of the Kindle to market and advised on the first Echo and Fire TV products. He also worked as the VP of Product Design at the healthtech startup, PillDrill, which shipped an award-winning medication tracking system. He is now a Mechanical Engineer at Agtonomy, an autonomous tractor startup. 

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