Inkjet printer

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Revision as of 04:21, 7 March 2007

Executive Summary

We are dedicating our effort on improving the functionality of a typical Inkjet Printer in this project, As of Febuary 12th, 2007, we have completed the product analysis (shown below) at a depth that we consider as sufficient to properly enter the actual designing stage. Because of the complexity of the product, the analysis below only involves the components we consider most relevant to our design ideas/goals. For additional/complete information, please check howstuffworks.com or other web sources.

Based on our analysis, we have also come to the conclusion that the components of a typical printer have been optimized not only in their functions but their manufacturing/assembly methods. Although the FMEA yields oppotunities for improvement on several components of the printer, those problems could have been addressed efficiently through proper usage and care of the unit. Therefore, we are suggesting to focus the design effort on improving the overall functionality of the printer instead of specific components.

The list of parts under Modification will be directly affected by the additional functionality we are currently planning to design. Other than Part 4, all the parts have to be either re-positioned or modified to generate the required space for additional components resulting from the next stage of design. For example, we might have to cut a hole/slot in Part 5 and attach an additional tray to it for CD/other hard materials' input. Vertical space is the most obvious issue as of now, and we will address these areas as we progress this project to the next stage. Finally, we will also look into ink cartridge situation to see if significant improvement can be achieved.

Inkjet_Printer_temp

Inkjet_Printer_Notes_Spring_2007

Product Study

We have identified five categories for the product study. This product study is served as initiation of our thought process and representation of our point of view in approaching the design. The primary goal of the study is to identify oppotunities in generating unconventional and advanced usage of a typical printer through design improvements.

Function
1. To print images in color or black&white or gray-scale on certain sizes of paper
2. To print images on a variety types of paper that have a certain softness level

Inputs/Outputs
Input
1. Paper
2. CPU data
3. Ink
4. Energy

Output
1. Printed paper

Functional Operation
1. Place Printer on a flat surface
2. Plug in Parallel (or USB) port to CPU
3. Plug in Power Cord to outlet
4. Install Printer Drivers
5. Insert Ink
6. Insert material to be printed
7. Upload Image desired from CPU to Printer
8. Remove Printer Image (End Product)

Different Users
1. Someone inexperienced with computers.
2. People who want to print images on special materials that are not bendable.
3. Physically Disabled/Elderly.

Other Stakeholders
1. Printer/Paper/Ink/Others Manufacturer
2. Providers of Raw Materials
3. Retail Stores
4. Transportation workers

Component List 1: Primary List

In the following list, we have identified all the components existed in a regular injet printer through two formats- "specific compnent" and "assembly". The next two sections will identify crucial sub-assemblies and provide a brief analysis for each.

Part #	Part Name	QTY	Function	Materials	Dimensions(*inch)	Manufacturing Process	Picture
1	Lid	1	Prevents dust; allows ink replacement & paper adjustment	Plastic	8x3x1	Injection Molding
2	Paper Tray 1	1	Holds pre-printed paper in straight position	Plastic	n/a	Injection Molding/Assembly
3	Paper Tray 2	1	Holds printed paper	Plastic	n/a	Injection Molding/Assembly
4	Input Buttons	1 set	Lets users input basic operation commands	Plastic/Others	n/a	Injection Molding/Assembly
5	Rear Cover Assembly	1	The 6 rollers located on the cover assist the paper movement in side of the printer	Plastic/Others	8x2x1.5	Injection Molding/Assembly
6	Upper Paper Supporter	1	Holds the printing paper in vertical direction	Plastic	7x2x1	Injection Molding/Assembly
7	Middle Paper Supporter	1	Provides constant upward forces to the printing paper	Plastic	7x2x1	Injection Molding/Assembly
8	Front Paper Roller Set	1	Rolls the paper out of the roller/supporter assembly	Plastic/Others	n/a	Molding/Assembly
9	Springs set	1 set	Acts as an simple shock absorber for the interior supporter	Metal	n/a	*Spinning
10	Rear Upper Plate	1	Serves as the provider of opposite force on the Springs against the interior paper supporter; allows wirings to be attached	Metal	7x2x.5	Stamping
11	Paper Feed Sensor	1	senses the paper right before being printed	Plastic/Others	n/a	Molding/Assembly
12	Rear Paper Roller Assembly	1	Rolls the paper into the first stage of printing process	Plastic/Metal	n/a	Molding/Extruding/Assembly
13	Lid Sensor	1	Senses the opening/closing of the lid to trigger the movement of other interior components such as the ink cartridge	Plastic/Others	n/a	Molding/Assembly
14	Main Bracket	1	Holds major components in place, including the brackets holding the motor and rear supporters	Metal/Alum	n/a	Stamping
15	Primary Chip Board	1 set	Responsible for the input/output/power signals	Plastic/Others	n/a	Others
16	Power Supply	1 set	Converts the voltage supplied by the power supply input from AC to DC	Plastics/Others	n/a	Assembly/Others
17	Inkjet Cleaner Unit	1	Keeps the head of the inkjet cartridge clean in between the operations to prevent the hardening of ink and jamming of the cartridge	Plastic/Others	4x2x2	Molding/Assembly
18	Inkjet Catridge Craddle	2	Holds the Inkjet Cartridge and transports it during the printing process	Plastic/Assembly	2x1x2	Molding/Assembly
19	Paper Roller Encoder Gear	1 set	Sends information to an encoder so that the printer knows how far the paper has traveled inside the printer	Plastic/Metals/Others	n/a	Molding/Assembly
20	Paper Roller Motor	1 set	Supplier the mechanical energy to the paper rollers so that can move	Metals/Others	n/a	Casting/Others
21	Inkjet Cartridge Craddle Motor	1 set	Supplies mechanical energy to the Inkjet Cartridge Craddle so that it can move	Metals/Others	n/a	Casting/Others

Component List 2: Sub-Assembly Analysis of the Main Gears *Part 19, 20, etc.

This sub-assembly is the set of gears that turns both the main and paper-pickup rollers. It also engages or disengages both the paper ejector mechanism and the paper loading mechanism. It is quite a complicated system, but is also quite ingenious. The picture below gives a breakdown of the different sets of gears and how they are connected. Much of this sub-assembly is left intact because of both the complexity of the overall project, but also because some of the parts would be destroyed in the process of taking them apart.

Description of power transmission:

1. The axle (axle1) labeled main rollers/encoder motor is the source of power for this sub-assembly. It is also the same axle that the main rollers are on. The power is derived from the encoder-motor sub-assembly. The encoder-motor assembly turns a gear on this axle (not shown in diagram) which also has an incremental encoder on it which gives feedback on how far/fast the rollers have turned.
2. The gear (gear1) shown in the diagram which is attached to axle1 is what directs power to both the paper-pickup rollers and the paper-feed-lever/paper-ejector-mechanism.
   1. The medium sized gear (gear2) just to the left of gear1 is what directs power to the paper-pickup roller assembly as well as to the small gear (gear3) to the left of gear2.
      1. Gear3 is used when the current print job is done and the printed paper needs to be ejected and a new piece needs to be picked up. When the print-cartridge carriage moves directly above the gearbox (as labeled in the diagram) a lever pushes the gearbox so that gear3 engages the gear (gear4) with a cam on it. This gear then turns allowing the paper-feed-lever to rise and load paper into the paper-pickup rollers. At the same time a lever (labeled [4] in the diagram) attached to the paper ejector mechanism is pushed, ejecting the printed paper. When a new piece of paper is loaded, the printer-cartridge carriage moves away from the gearbox, disengaging gear3.
   2. The other medium sized gear (gear5), below gear1, now transfers power to the smaller gear (gear6) below it.
      1. Gear6, by default, is now engaging gear4. Now gear4 turns again returning the ejector mechanism to its resting position and dropping the paper-feed-lever back down. When everything is back in place gear6 reaches the bare spot on gear4 and stops turning it. Since gear6 can now freewheel, the printer is free to move the rollers in order to get the printheads into place.

Component List 2: Sub-Assembly Analysis of Paper Roller Encoder System, *Part 19

Subassembly analysis of paper roller encoder system: The subassembly consists of three main components that act as a feedback control system: 1- The encoder circuit 2- The driving motor 3- The encoder gear

1- The Encoder Circuit This circuit is responsible for sending information the to the main printer circuit board. The circuit board sends information about many degrees did the paper roller turn. With this information the main circuit board can keep track of where the sheet of paper is inside the printer. The Encoder Circuit determines this information by using an infrared laser that monitors the movement of the encoder gear.

2- Encoder Gear This gear is directly attached to the Paper Rollers. There is a plastic disc with several small black lines along its circumference. The purpose of the black lines is provide a reference for the infrared laser. As the encoder gear moves the black lines are seen by the infrared laser to as a series of ones and zeros or black line and no black lines. By counting the number of black lines that were crossed the encoder can determine the number of degrees that the encoder gear turned. Using this and by knowing the size of the gears the main circuit board can determine the distance that the sheet of paper has traveled in the printer.

3- Driving Motor The driving motor is the final part of the feedback control system. The motor receives signals from the Encoder Circuit that tells it when to start moving and stop moving. The motor is also geared up to provide additional torque for moving the paper.

Design Considerations

We have identified six aspects for design considerations in order to locate any design oppotunities. Throughout the analysis, it is evident that the manufacturing aspet of the product has been optimized while the only clear design oppotunity lies in the environmental aspet of the design. The initial conclusion is to focus the approach on improving either the efficiency of power and ink usage or on looking to add functionality to the product according to the result of the product study.

Design for Assembly

• Visible and hidden screws are presented in many areas among the brackets/chip-circuit board/etc to secure every major parts onto the base
• Brackets/major assemblies are positioned in a way that they have to be put on/off together
• Many of the parts are designed with an interlock which is held in place by one screw. This reduces the number of screws and bolts which makes assembly much simpler and inexpensive.
• Almost all of the plastic parts, from the lid to the gears, have snaps that allow them to be easily attached to the main body.

Design for Disassembly

• Primary bracket has to be loosen before any other major components can be disassemble/removed from the base
• Difficult to assemble the pieces back to the original state once disassembled
• Great amount of sub-assemblies present throughout the unit
• Many of the plastic snap pieces are not easy to remove once they are in place. Many of the clips are on the inside or out of sight, making it much tougher to see and release them.

Design for Environment

• Plastics are not biodegradable
• Ink and Power usage by the users
• The overall reliability of the product is good enough for the unit to last long enough time to make up for the main materials' harmful environment effects

Design for Manufacturing

• Brackets and major componets are placed in a way that they must all be at the correct position before being fastened with screws to ensure a secure overall fit

Design for Reliability

• With proper care/upgrades, the product has a very long life
• Nearly impossible to take apart without proper tools and dedicated intention
• The main wearing component- ink catridge, is very replaceble

Design for Saftety

• Proper covers/lids prevent unwanted interaction between human hands and running machinaries
• Sensors prevent excessive/active interaction between hands and mechanical components once they are exposed

Design Usability

• CPU/other wirings must be present for input purpose
• Paper tray assemblies' straight shapes helps to position the papers

FMEA chart

We have identified three FMEA items based on the initial conclusion of the product analysis. The conclusion has led us to focus on locating items that directly relate to user operation, since the inner operation of the product is identified to be optimized. The list contains items that can be avoided with proper user care and usage.

• S: Severity of failure
• O: Occurance probability
• D: ease of Detection

Modification, based on "CD Printing Concept"

Our current analysis have generate the following list of components for possible future design development:

• Part 4- Input Buttons: improving user interface
• Part 5- Rear Cover Assembly: possible CD insertion slot location
• Part 6 through 8- Main Roller/Supporter Assembly: modified to generate addition vertical space
• Part 9 & 10- Springs and their resting plate: relocated to generate space for CD slot
• Part 12- Rear Paper Roller Assembly: modified to allow CD carrying movement
• Part 14- Main Bracket: redesigned to generate additional space for new components

Areas of Possible Improvement

The list of parts under Modification will be directly affected by the additional functionality we are currently planning to design. Other than Part 4, all the parts have to be either re-positioned or modified to generate the required space for additional components resulting from the next stage of design. For example, we might have to cut a hole/slot in Part 5 and attach an additional tray to it for CD/other hard materials' input. Vertical space is the most obvious issue as of now, and we will address these areas as we progress this project to the next stage. Finally, we will also look into ink cartridge situation to see if significant improvement can be achieved.

Brainstorming as of Feb 15th, 2007

• Initial Idea: Create a slot load on the back of the printer and make the rollers adjustable so that thicker or unbendable material can be printed on. This material could be a CD, cardboard, or just thicker paper (e.g. construction paper).