#531: Jaggedges

The human visual system is particularly good at detecting small misalignments (ie as small as the width of a pencil viewed at 300m).

Today’s invention makes use of that fact to help provide screen displays which are less susceptible to ‘shoulder surfing.’

Such tiny misalignments in gratings of lines can be seen, but only when viewed from straight ahead. A shape can thus be seen in the diagram, formed simply by small jumps in the black lines. These jumps, and the shape, would be much less visible to anyone observing them from, in this case, the 10 or 4 o’clock position.

The display on eg an ATM touchscreen could flash up an array of apparent numbers formed from misalignments in a grating and a bank customer could then choose their pin number, without showing these digits to bystanders.

#530: WalkWheel

It had to happen sometime: IOTD reinvents the wheel (again).

A wheel (in this case of a bicycle) is replaced by two sectors. Each of these can rotate independently about their common axle. The bicycle is moving right to left. When the sector marked ‘a’ has come close to the end of its tyre’s contact with the road, the other sector marked ‘b’ is flipped around the axle counterclockwise to take its place, just in time to provide smooth forward motion (with much lower rotational inertia than normal).

Such a setup requires a spring mechanism to drive the sector and a robust trigger to activate the process. The axial spring would be wound by the forward motion of the machine and the triggering could be quite crudely coordinated using a mechanical latch.

This arrangement also allows a greatly reduced weight and space requirement for a fold-up machine. It’s also rather a cool way to ride about, always looking as if one is about to fall off.

Rather than flip counterclockwise from a to b, the sectors might swap places by raising the rear one off the ground and ‘stepping’ clockwise from position a to b (at the cost of added complexity). This would save some frame height (and the cost of material) as well as reducing the energy drain from the system.

#529: Rollerr

The scroll wheels on computer mice seem to be highly variable in terms of the precision with which they locate the cursor. I know this because today’s invention is a technique for quantifying these errors.

Open up your favourite browser and point it at Google maps. Now you can centre the map on some prominent feature (I use a huge, white-roofed exhibition hall in Vancouver). Next, secure the mouse to the desk (duct tape works, as ever) and use the scroll wheel to zoom out to ‘space’ and back a fixed number of times (say 5). Record the new screen centre location on the map (this will have changed, in general, due to sloppiness in the way the scroll wheel mechanism works). If you can stop the hypnotic process of zooming in on terra firma, eventually you will have characterised the on-screen precision of your scroll wheel.

This probably isn’t important for most users, but I understand that it affects some games players’ performance. In addition, if you have identified a brand of scroll wheel which operates with known, high accuracy, this could then be used to detect any hand tremor in users of an untethered mouse.

#528: Coolometer

Many thermometers operate on the basis that some internal fluid expands when heated.

Today’s invention turns that on its head by making a thermometer consisting of a fluid with a very low coefficient of thermal expansion (eg coloured water) in a glass enclosure which expands greatly on heating (eg soda glass).

When this device comes into thermal equilibrium with something hot, the glass will expand, whilst the liquid stays at almost constant volume. The temperature will thus be measured by the fall in the liquid level.

Similarly, a temperature fall will be registered as a rise on the coolness scale.

#527: Frugasity

Today I was reading one of those increasingly hysterical stories about how the high price of ‘gas’ is causing US drivers to consider more economical driving techniques (£1.12 per litre is what I’m paying in the UK…probably enough to cause a riot if the US govt inflicted our levels of tax over there).

Anyway, one of the suggestions I read was to drive as if one were on a pushbike…ie to live with a reduction in speed whenever the vehicle engine suddenly comes under increased load eg when heading uphill. Most people have a tendency to sink their right foot and try to maintain uniform speed, so this seems like reasonable advice.

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Today’s invention is a modification to the accelerator pedal which helps implement this regime and save fuel. A tlit sensor detects when the vehicle is heading uphill. Other sensors measure the load being pulled and the weight of its occupants. These data are interpreted by a hydraulic resistor which makes the pedal harder to depress when the engine is experiencing such harsh demands.

Gradual changes in loading, such as in smooth overtaking, could be arranged not to affect the accelerator pedal stiffness in this way.