In this blog I will give you a brief summary of the Combimouse design history. I have made many prototypes over the years. At the time it was invented, technology wasn’t available to make it a reality. There were also difficult design obstacles to overcome.
I will refer to the Old prototype shown below as “OLD”. OLD has a mass of 194 grams. The centre of gravity is located somewhere along the red line. This is what the Combimouse looked like in 2012.
The latest prototype (as of April 2013) is shown in the following sketch and has a mass of 74 grams (this includes 26 grams of lead weights to optimise the centre of gravity and weight distribution). I will refer to it as “LATEST”. The centre of gravity is located somewhere on the red line. It is 120 grams lighter than OLD and lighter than most regular mice.
As a comparison, below is the Apple Magic which has a mass of 108 grams. The centre of gravity is located somewhere along the red line. It is 34 grams heavier than the Combimouse.
Originally with OLD, I thought that the palm grip had to be bulging. This was necessary so that it would fill the palm of the hand while using as a mouse. This was especially true up until a few years ago, when the right part was heavy and a good grip was necessary.
The problem is that this bulge made it uncomfortable as a palm rest during typing. As a palm rest it has to be flat and low. Also when I used to move my hand when typing I would bump into the large bulge and the whole unit would move.
On OLD, I was using AA batteries that have a diameter of 14mm. Also on OLD I wasn’t aware that height is an issue – I have subsequently discovered that the top of the keys must be as low as possible. The height of the top of the keys above the desk on OLD is 27mm. On Latest it is 14mm. So LATEST is much lower and that makes typing much easier.
In addition the mouse click keys are now much lower and better.
Apple started selling the Apple Magic Mouse a few years ago. I was surprised that it didn’t have a bulge to fill the bottom of the hand. They made it very flat and low. This is probably a compromise so that they can make the surface a flat touch sensitive surface for gestures. Apple supplies this mouse with all their Macs.
Last year (2012) I realized that if Apple can do this then so can I. I can now have a low flat surface for the palm rest/palm grip, which is ideal as a palm rest during typing. It is also good enough as a palm grip during mouse mode especially now that LATEST is light and doesn’t need a firm grip. This was a major breakthrough.
In addition electronics have reached a point where power consumption is very low. Today a common Logitech wireless mouse has over 1.5 years battery life. So the Combimouse, which has a relatively high current consumption, can use the lighter and smaller AAA battery. This makes LATEST lower and lighter.
Mass of Keyboard Section
It is critical to make the mass of the Keyboard section as low as possible so that it isn’t top heavy during mouse mode. Even 1 gram is a lot. Notebook Keyboard technology has slowly improved to a point where keyboards are very light.
In addition thin plastic walled devices are now possible allowing for a light Combimouse. One mm thick walls are now easy. This is mainly due to advances in mold flow analysis software, which occurred in the last few years.
This progress in technology makes a light design possible.
There are two main conflicting design obstacles that had to be overcome with the Combimouse:
- Make it mobile as a mouse
- Make it immobile as a keyboard.
To make it mobile as a mouse it was necessary to reduce the mass and achieve a favorable center of gravity and low moment of inertia. What this comes down to, is making the mass of the keyboard section as low as possible. I have got it to a point where the area bounded by the Equal, Seven, Space and Shift keys is about 15 grams. This took a long time. I have been liaising with the manufacturer to check that this solution is manufacturable. They think it is manufacturable, but would need to use software flow analysis to confirm this and this costs money.
The problem of making the unit immobile as a keyboard was a difficult problem. Earlier this year (2013)I decided that I needed a radical change to solve this problem, as I wasn’t getting anywhere. I have now devised a solution. Unfortunately I can’t talk about the solution, as I will be patenting it.
After all these years it is a relief that this problem has been finally resolved.
As a result the Combimouse works well as described in the blog “What’s it like using the Combimouse?“.