Photocopiers

The purpose of photocopiers is to create a clear picture – a picture that’s an exact duplicate of the original. Look at the word – photocopy. Photo – picture of. Copy – duplicate. So, as we said, a photocopy is a duplicate of the original picture. But how could an exact copy be created? What kind of technology would it involve? Would it surprise you that the technology behind photocopying is based on two natural phenomena?

The amazing thing about how photocopiers work is the nature of these phenomena. These principles are:

1. Materials of opposite electrical charges attract, and

2. Some materials become better conductors of electricity when exposed to light.

When Chester F. Carlson applied these principles to his work – to find an alternative method of duplicating for the myriad of reports he had to produce – the result was the basis of today’s photocopier, printer and fax machine technology.

[edit] The basic principles of photocopying

Chester Carlson’s experiments followed a simple process:

1. A photoconductive surface is given a positive electrical charge.

2. The photoconductive surface is then exposed to the image of a document.

3. The electrical charge dissipates in the exposed areas.

4. Negatively-charged powder that’s spread over the surface sticks to the positively-charged areas through electrostatic attraction.

5. A piece of paper is placed over the powder image and given a positive charge.

6. The negatively-charged powder is attracted to the paper as it’s separated from the photoconductor.

7. Heat fuses the powder image to the paper, producing a copy of the original image.

[edit] These factors affect copier energy use:

• Warm-up time- If the machine warms up quickly, it can be switched off when you're not using it. The best office copiers warm up in less than 10 seconds, while small home office machines warm up even more quickly.

• Consumption while copying- Electricity consumption while copying varies from a few hundred watts to several kilowatts, generating from a quarter to more than three kilograms of greenhouse gas and costing from four to 45 cents per hour of continuous copying. Each time you start photocopying, the machine uses extra energy to get ready to operate.You can save energy by "batch copying," which involves saving up your copying tasks and doing them in one batch.

• Standby consumption when switched on but not copying- Keeping the operating components of your photocopier warm or "on standby" ready for immediate copying uses from 15 to 400 watts of electricity. This generates a kilogram of greenhouse gas every 2.5 to 65 hours and costs from 0.2 to 6 cents per hour. It is far better to power-manage your machine.

• Power management features- Some older models of photocopiers have "energy save" buttons which are supposed to reduce energy consumption while on standby but which in reality save little or no energy. However, the newer ENERGY STAR photocopiers include an efficient energy save button in their range of power management features.

• Energy consumption when switched off- Some copiers have small electric elements of up to 50 watts that operate continuously unless the photocopier is switched off at the power point.These are only needed in humid environments

• Energy consumption of accessories- Document feeders and collators may consume a lot of energy if they don't power down with the rest of the machine.You can see in Figure 5 the greenhouse gas emissions from photocopiers operating under different power management regimes.

See How photocoppier works to know about the functioning of photocopier.