Liquid crystal displays
- LCD's consist of organic carbon based compounds held within a cell.
- When the cells have a small voltage applied to them they go dark.
- Controlling the voltage application to a number of cells means a controlled dark area can be created.
- Straight lines, simple shapes, generally not much colour.
- Image clarity and flexibility.
- Low voltage and slim screen.
- Organic carbon based compounds used.
- Ideal for portable electronic devices such as mobile phones, as battery life can be extended.
- Expensive set up and low light viewing difficult.
- Viewing angle often not good.
- After glow material.
- Absorb light energy or 'charge' in normal conditions and are capable of storing the energy for some time, then releasing it relatively slowly in the form of light.
- Can be manufactured into polymers used in pains or inks for products like safety signage and watch faces.
- Can be seen in complete darkness.
- Can glow in complete darkness.
- Recharge in normal daylight.
- Organic compound and no cost to run, with no power source required.
- Colour limitations and initial set up cost is much more expensive.
- Electroluminescent lighting converts electrical energy into light by applying a voltage across electrodes.
- The current charges phosphor crystals.
- Visible light is emitted and a much lower power consumption.
- Produced as wire, or strips and can be sandwiched very thinly.
- Ideal for back lighting LCD displays (posters and adverts) or watch face lighting due to low voltage.
- Organic compound and a low running cost.
- Very low power consumption and ideal for back lighting.
- Can form highly visual impact images and can also be waterproof.
- Very reliable.
- Colour limitations and initial set up cost is high.
- Can be deemed to be low tech compared to LCD images.
Thermochromic Liquid Crystals
- Changes colour in temperature, used for forehead thermometers, battery test panels and special printing effects.
- In the case of forehead thermometer:
- A layer of conductive in is screen printed onto the reverse of the thermometer strip.
- On top of the conductive ink is a later of normal ink that conveys the temperature gauge colour bars.
- Finally, there is the thermochromic later, which is black when cool.
- By pressing the thermometer to the forehead, the temperature generated turns the thermochromic ink translucent.
- When pressed/squashed it gives off electricity.
- It is a material that expands and contracts when electric current is applied.
- The piezoelectric effect converts this mechanical stress or vibration into electrical signals and vice versa.
Actuator: a device for controlling a mechanism or system.
Example: musical greetings card
Process: the musical module is activated by opening the card, which removes an insulating tongue from between a pair of switch contacts on the module. The piezoelectric crystal acts as a tiny speaker driver allowing it to generate a pre-programmed sound stored on an integrated circuit mounted on the module.
Transducer: a device that converts a signal from one form to another.
Example: electronic drum kit
Process: when an electronic drum pad is struck, a voltage change is triggered in the embedded piezoelectric transducer. The resultant signals are translated into digital waveforms, which produce the desired percussion sound assigned to that particular trigger pad.
Smart Ink/Electronic Paper
- Smart ink is a display technology designed to mimic the appearance of ordinary ink on paper.
- Electronic paper was developed in order to overcome some of the limitations of computer monitors.
- A prime example is the kindle.
- Each pixel point on the display is a tiny pit containing a small number of black and white beads, each of which is about as wide as a human hair.
- The white beads are positively charged and the black beads negatively charged.
- Each pit is topped with a transparent electrode and has two other electrodes at its base.
- Altering the charge on the base electrodes makes either white or black beads leap to the top of the pit forming either a blank or black spot on the larger display. Making on base electrode positive and the other negative creates a grey spot.
- The pixels have an inherently stable 'memory effect' that requires no power to maintain an image.
- Displays only draw on battery power when text is refreshed, which means they can display about 10,000 pages before the batteries need changing.
- Flexibility of surgace and it doesn't run down voltage.
Radio Frequency Identification (RFID)
- Radio frequency identification is a method of identification that uses tags stuck on to a product to store date that can be retrieved by a reader.
- This method is often used to track pallets of products from the manufacturer to the retailer.
- RFID technology is based on the transmission and reception of radio frequency signals between a transmitter (know as a reader) and a transponder (known as tag), which is attached to the product.
- In most cases the transmission is two way; the transmitter sends signals, which the transponder recieves; the transponder then transmits a response signal that is recieved by the transmitter.
- The information from the transmitter can then be usd to identify the transponder and any item it is attached to.
- Softwoods: stronger and longer grains.
- Hardwoods: smoother and shorter grains.
Properties: low density, straight grain and fine texture.
Properties: extremely buoyant, very soft and light and low density with high strength.
Scots pine: softwood
Properties: easy to work, knotty and prone to warping.
Parana pine: softwood
Properties: hard, straight grain, fairly strong, durable and easy to work with a smooth finish.
Properties: fairly strong, but not durable. Easy to work and very resistant to splitting.
Composition: usually consists of a bleached virgin pulp top surface, unbleached pulp middle layers and a bleached pulp inside layer.
Applications: Widely used for the majority of food packaging and for all general carton applications.
- Excellent for scoring, bending and creasing without splitting.
- Excellent printing surface.
Composition: Constructed from a fluted paper layer sandwiched between two paper liners.
Applications: Protective packaging for fragile goods, the most commony used box-making material.
- Excellent impact resistance.
- Has excellent strength for its weight.
- Low cost and recyclable.
Solid white board
Composition: Made entirely from pure bleached wood pulp.
Applications: Packaging for frozen foods, ice-cream, pharmaceuticals and cosmetics.
- Very strong and rigid.
- Excellent printing surface.
Composition: Consists of a laminated foil coating. Foil available in matt or gloss finish and in silver or gold colours.
Applications: Cosmetic cartons, pre packed food packages.
- Very strong visual impact and foil provides an excellent barrier against moisture.