4 Printers and Multifunction Devices Flashcards
What are impact printers ?
The most basic type of printer is in the category known as an impact printer. Impact
printers use some form of impact and an inked printer ribbon to make an imprint on the paper. Impact printers also use a paper feed mechanism called a tractor feed that requires special paper.
There are two major types of impact printers: daisy-wheel and dot-matrix.
What are Daisy-Wheel Printers ?
One of the oldest printing technologies in use. These impact printers contain a wheel (called the daisy wheel because it looks like a daisy) with raised letters and symbols on each “petal”. When the printer needs to print a character, it sends a signal to the mechanism that contains the wheel. This mechanism is called the print head. The print head rotates the daisy wheel until the required character is in place. An electromechanical hammer then strikes the back of the petal containing the character. The character pushes up against an inked ribbon that ultimately strikes the paper, making the impression of the requested character.
Letter Quality (LQ).
What are Dot-Matrix Printers ?
The other type of impact printer to understand is the dot-matrix printer. These printers contain rows of pins that are triggered in patterns that form letters and numbers as the print head moves across the paper
Near Letter Quality (NLQ).
What are Inkjet printers ?
These printers spray ink on the page to form the image. Inkjet printers typically use a reservoir of ink, a pump, and a nozzle to accomplish this.
The printer parts can be divided into the following categories:
Print head/ink cartridge
Head carriage, belt, and stepper motor
Paper feed mechanism
Control, interface, and power circuitry
Parts of an Injet Printer:
Print head/ink cartridge
Head carriage, belt, and stepper motor
Paper feed mechanism
Control, interface, and power circuitry
What is a print buffer ?
A small amount of memory (typically 512 KB to 16 MB) used to store print jobs as they are received from the printing computer. This buffer allows several jobs to be printed at once and helps printing to be completed quickly.
Once the printer is ready to print:
The control circuitry activates the paper feed motor. This causes a sheet of paper to be fed into the printer until the paper activates the paper feed sensor, which stops the feed until the print head is in the right position and the
leading edge of the paper is under the print head. If the paper doesn’t reach the paper
feed sensor in a specified amount of time after the stepper motor has been activated, the Out Of Paper light is turned on and a message is sent to the computer.
What are page printers ?
Printers that receive their print job instructions one page at a time rather than receiving instructions one line at a time.
Two major types of page printers that use the electrophotographic (EP) imaging process:
The first uses a laser to scan the image onto a photosensitive drum
The second uses an array of light-emitting
diodes (LEDs) to create the image on the drum.
Most printers that use the EP imaging process contain nine standard assemblies:
the toner cartridge, laser scanner, high voltage power supply, DC power supply, paper transport assembly (including paper-pickup rollers and paper-registration
rollers), transfer corona, fusing assembly, printer controller circuitry, and ozone filter.
What is the fuser ?
The fuser is made up of three main parts:
a halogen heating lamp,
a Teflon-coated aluminum-fusing roller
a rubberized pressure roller.
The fuser uses the halogen lamp to
heat the fusing roller to between 329° F (165° C) and 392° F (200° C). As the paper passes between the two rollers, the pressure roller pushes the paper against the fusing roller, which melts the toner into the paper.
What is the printer controller assembly ?
A large circuit board that converts signals from the computer into signals for the various assemblies in the laser printer using a process known as rasterizing. When a computer prints to a laser printer, it sends a signal through a cable to the printer
controller assembly. The controller assembly formats the information into a page’s worth of line-by- line commands for the laser scanner. The controller sends commands to each of the components, telling them to wake up and begin the EP imaging process.
What is Duplexing Assembly ?
Usually located inside or on the back of the printer, the assembly is responsible for taking the paper, turning it over, and feeding back into the printer so the second side can be printed.
Electrophotographic Imaging Process:
The electrophotographic (EP) imaging process is the process by which an EP laser printer forms images on paper.
- Processing
- Charging
- Exposing
- Developing
- Transferring
- Fusing
- Cleaning
Before any of these steps can begin, however, the controller must sense that the printer is ready to start printing (toner cartridge installed, fuser warmed to temperature, and all covers in place).
Step 1: Processing
The processing step consists of two parts: receiving the image and creating the image.