Touch screen coffee table computer Version 2.0. Based on an LED TV and a IR touch frame with selection buttons for Windows 8 and Android.
In my previous post I outlined my interest in large format touch screen computers. So as 2013 grew to a close, I started to look if technology has moved enough in the last 2 years to build something new. I had several bullet points to hit in order to justify the expense of building a new coffee table computer. It had to work better, or more to the point, it had to work without having to be constantly maintained with shifting drivers, and light conditions. It had to fit into a smaller footprint. With becoming new parents, we came to realize that a space in the room currently occupied primarily by the coffee table, had to be shared. The table had to get sleeker, if not smaller. The table had to become a real piece of furniture. The first table was built as a technical experiment, this one would be built based on the lessons of the first and would take form into account as much if not more than the touch screen functionality.
The first table was built on a projector, and camera system for detecting touches, this had to change in this table. The projector is replaced by top end LED TV. The camera system was replaced by a IR frame. The frame, by PQ Labs was the answer to the question — how to make the coffee table computer an actual table, and low enough to the ground to be called a coffee table. With the technology of the touch interface simplified, additional pieces of electronics were introduced. The touch frame included support for Android, and came included with an Android stick computer, so an HDMI KVM switch would be needed. A lesson from the first build where the SD car/USB hub was added after the build was complete, in this build it would be included from the start.
Design of the Table
The table would be a table — top panel to house the TV, touch frame, a tough mar-resistant acrylic as top surface. I was going to re-use the quad marine speakers from the first build, as well as 2 of the fans.
Mounting the TV
The TV would rest on ribs as I called them — the Samsung TV I selected is just under 2 inches thick at it’s thickest point, so the ribs would be a total of 4 1/2 inches high to provide sufficient air flow and enough clearance between the base of the top for speakers and a fan.
I made the ribs out of 3/4″ plywood and cut them using a cardboard template to snugly fit the TV.
Speakers and Fans
The speakers and fans were mounted inside the top panel — with reusing the marine speakers and fans the profile of the top panel could be kept as thin as possible.
Protecting the TV
The protect the TV from damage of being a coffee table, I got a 0.4 inch thick piece of mar resistant acrylic. The ribs which I mentioned before would also serve to bear the weight of the acrylic since I did not want to rest it directly on the bezel of the TV.
The acrylic top also rests on 2 pieces of 4 1/2 inch plywood a short distance from each side of the TV. Thus the acrylic is fully supported by the structure and does not come in direct contact with the TV.
The center column of the table houses all the computer electronics and wiring. I’m not a neat freak by any means as far as wiring goes, so following are a few shots of the center column and the front panel.
The power system is similar to the first table — 12V DC current from the PC closes a 12V relay, which turns on an outlet turning on the rest of the components — in this case the TV, 12V power supply to power the fans, and the sound system. However, now there is a separate latching switch which closes another relay which also makes this outlet live. This latching switch allows to turn on the table without turning on the Windows PC, thus enabling the use of the Android stick computer independently.
The front panel in this build is removable, so all the electronics can be easily reached for any future maintenance. The front panel holds the KVM switch, 2 power switches (momentary for the Windows PC, and a latching switch for Android), a USB 3 hub/SD card reader, and the volume control for the quad speaker system.
Initially the Android stick computer included with the touch frame was a nice bonus, but as the build progressed, it became a key piece of the build and a deciding point for other components. The Android experience became more key to this build due to lessons learned from the first build. Windows 8.1, is still not a mature touch oriented OS. The market place is too bereft of useful applications to justify a fully touch centered experience. Android on the other hand is a fully capable touch OS, so having the ability to switch to Android as needed became key for this build.
Construction of the Table
The key lesson learned in the first build, is that everything had to be easily accessible for maintenance. This may not be necessary after all the kinks have been worked out, but during the debugging stage, after the initial build is finished, ability to easily get to the inside of the table is crucial. To do this, I built the table in 3 pieces. The center console (3 sided) with the top panel and ribs for the TV/acrylic mounting. The top frame which is constructed to have just the screen visible, and a routed edge for wires as well as the touch frame. Finally the front panel shown above which has all the tactile elements for turning the table on, switching between OSes, volume control, etc.
Finishing the Table
Last build was my first real entrance into building furniture, so there were a lot of mistakes and a lot of lessons learned, as I’ve mentioned several times already, so on this build — a water based stain was ruled out early. The look and the feel of the piece just can’t be achieved by using a water based stain the same way an oil based polyurethane can. So I went with an antique glossy walnut stain. This stain is a stain and and poly in one. I applied 2 coats to get the desired finish strength, to do that I had to move the piece into the garage for a couple of days in order not permeate the house with the smell. The poly ended up being very shiny, too shiny in fact, however after going over it a few times with a fine steel wool, the look met wife’s approval.
In order to make the 3 pieces of the table come together and be modular, I went with a decorative bolt + threaded insert system. I had used this approach in the past on the first build — but the usage on this table was a lot more ambitious. The plan required that I drill perfectly straight holes for 12 threaded inserts in the top side panels. This was accomplished with a jig made on a drill press. The jig was then clamped to the side panels and made drilling the 12 holes doable. To then give the threaded inserts more strength, after testing the assembly, I applied crazy glue on the threads before inserting them into the the pre-drilled holes. The crazy glue works perfectly when using threaded inserts with plywood.
The finished table has a smaller footprint, takes less space in the room, while actually increasing the image size from 42 to 46 inches on the diagonal. Also with a switch between Android and Windows, a wide range of applications can run on the table.
Every new project should be a learning experience of some sort, otherwise the fun is lost. This was the first piece of furniture that I’ve built which doesn’t look home made. I had a few stain issues, but for the most part I am happy with the result. I was able to use all of he new tools I assembled in my workshop. In the first build, I relied on the hardware store to make many of my cuts, or the old standby table saw. A lot of those cuts were uneven, which made calibrating a very precise projection system very difficult. On this build, I use the Festool tracksaw, and a re-calibrated table-saw for other cuts (most cuts were done with the Festool saw, using the track system and the Festool MFT table). I also have made great use of the Kreg Jig to do pocket holes. A lot of inventive clamps and jigs made this build go a lot smoother. I still had to invent ways to work with a fairly large piece of furniture in a confined space. I used every inch of my workshop, and then some. There are minor things I’ve learned during the wood working aspect of this build which I will apply in future furniture projects. Other elements which proved complicated or difficult are the technical aspects of using a TV as a computer monitor. Newer TVs may not power back on when loosing power — a special HDMI adapter box is needed to have a computer trigger the TV to power on and power on to the correct input. Even though I fully intended to use this adapter, it became unnecessary as the Samsung TV I used returns to previous state upon powering up. Other complications to this build surrounded the Android experience. Android sticks are a relatively new market, so working directly with the manufacturer to get a sufficiently powerful Android stick working has been difficult. PQ Labs has been very helpful, and the majority of the slow downs have been due to the large time difference between US and China (where PQ Labs development is based).
This table, much as first one is really a solution in search of a problem. I’ll be the first to say that. It works really well to entertain kids, and I am happy to report it survived an attack of several children during a party we had. Kids love this, adults don’t know what to make of it, the cool factor is there, but I am still searching for an everyday use. I’m hoping after Android experience is upgraded (I expect to receive a quad core android stick end of this week or early next), the use cases may increase. Time will tell.