Plastic Parts for a Mouse - Report Example

1) Plastic parts of a Mouse Introduction Computer mouse is the most essential part of a desktop computer as the user is able to navigate through the websites as well as perform almost all the tasks by the use of the mouse only. The computer mouse has been designed to fit the curve of our hands so that we can easily operate it by pressing any of the three springs, inbuilt within the mousetrap. The pointing of the curser and click of the mouse gives the required instructions to the concerned personal computer for carrying out various tasks that may not be possible to be done through other MS modes of operation. While the rolling ball on the underside of the mouse help in the movement of the cursor on the computer screen, the three spring buttons on the right, left and middle of the mouse give clear instructions to the computer processing unit. As per article written by Holmes. S. Gillian in “How is a computer mouse made” (vol-5, 1997); Dr. Douglas Englebart worked as a professor with Stanford Research Institute at California. He was the first person to develop the computer mouse, during the year 1964. Computer operation was done only with keys from the computer key board until the discovery of the mouse. According to Gillian, the initial shape of the mouse was like a brick with two wheels that controlled the horizontal and vertical movement on the screen. Since the device was attached to the computer through a long cable, the scientists responsible for making this first time thought it to be a mouse with a tail. Hence, the name given to this device, that is still being used so widely in the computer industry. According to Holmes in the article published on “ how is the computer mouse made(1997); during the year 1973, Xerox combined the device with Alto computers, after a free rolling ball replaced the undercarriage of the mouse and on the top of it were three clickable buttons. This design is still prevalent with the present day mouse. Macintosh and Windows operating sytems later adopted this method of computing. This helped Engineers to draft, draw and make designs with the use of mouse. Making it as an input and output device with the maneuverability of the track ball of this device. During the later development, the mechanical devices (2) were replaced by the optical and/or electronic sensor systems. Thus, we have optical mouse available currently. Most of the parts of this device are made from various grades of plastic and the details about the same are given in the following pages. Parts of the mouse Mouse body Mouse is made of mainly two parts. These are called the brain and the body of the mouse. Material used for both these parts is plastics based, with little variations. The outer body of the mouse is made of hard plastic material and the tail is a cable, which connects the mouse to the CPU of the system. The three clickable buttons are external contacts for switches to complete the circuit and instruct the CPU for any particular function. According to Holmes, the undercarriage of the mouse has a rubberized ball with a plastic hatch. The ball remains in place with the help of a supporting wheel and two shafts. The movement of the shafts is for the horizontal and vertical guidance of the mouse, as the ball rolls on a plain surface. While each shaft turns with horizontal or vertical motion, as specified, a spoked wheel at one end of each shaft also turns. The revolutions of these spokes send infra red light emitting diode signals, which are intercepted by a light detector. The light and dark phases of the mouse movement thus created are converted into electrical pulses by the phototransistors present in the mouse body. These pulses are transferred to integrated circuits of the mouse. As discussed in detail by holmes (1997), these pulses give direction to the mouse for instructing the computer system CPU about the horizontal or vertical as well as left or right tracking movement of the ball and corresponding instructions from IC to the cursor for relative movement on the monitor screen. According to Holmes, the mouse has a printer circuit board (PCB), which has this IC also mounted on it. The data signals given to the computer are directed through this PCB via the concerned IC. Mouse brain The signals sent by any external device to the computer system need software that can understand these signals. Holmes (Computer mouse , Vol 5, (3) 1997, page 2) has described the role of this software, that is called the driver for the mouse. The driver helps the computer to interpret the signals of the mouse Hence, all data from the IC about the speed, direction and other commands are properly interpreted and implemented through this brain of the mouse...”the driver”. Most of the computers have built-in drivers for the mouse as part of the whole system. (A clean germ resistant, scanner and fingerprint enabled mouse As depicted in “20 computer mouse designs- 2008- available at http://www.interactivemaster.com/blog--computer--mouse--past--to--present.html figure 11, accessed on 27thMarch, 2009) Raw material used for Mouse manufacture Injection molded plastics is the basic raw material for most of the mouse parts. The outer body and its internal mechanical parts like spoke wheels and shafts are made of acrylonitrile butadiene styrene (ABS) plastic material. (4) According to Nugent Tim, (April 2008), the mouse can be water proof also by adopting the process of rubberized coating or over molding, as it will help to hide the gaps or any partitions in the mouse body. Design of a mouse As per Holmes(vol 5, page 2, 1997), the design of the mouse is a sensitive affair which requires the involvement of marketing, technical and a consulting agronomists, to deal with the human behavioral aspects of the mouse movements. The design inputs will include the sizes of the hand, touch sensitivity, amount of work handled by a particular hand size etc..Accordingly, the design will depend on these parameters along with the safety and security requirements. The office or the desktop physical conditions also matter while designing a mouse. The initial designs were made from wooden molds, followed by their testing for all these functions. CAD based designs are computer generated and three-dimensional shapes are used to machine cut the external shell of the mouse. This follows the incorporation of mechanical and electrical devices like IC and PCB on the mouse underside. The rubberized ball design is also determined with the help of CAD and its placement within the encoder mechanism is properly designed and tested till the optimum design requirements are achieved. Tooling requirements The tools and fixtures required to produce the mouse will need modification in the available tooling machines. The modification has to be carried out in accordance to the design parameters of the mouse diagram. Hence, tooling diagrams are computer generated for injection molding of the shell to take care of all the details of mouse making like the number of gates for plastic injection, size and shape as well as the cavity volume etc.. The tooling jigs and fixtures may require modifications for a number of times, to suit the actual performance criteria of the mouse. As per Holmes, (Vol 5 ,page 3, 1997), once the tooling program is finalized, design details tested and tools ready are for the job, test are conducted to determine that the trial mouse pieces meet the design parameters, the mouse is ready for mass production. (5) Mouse manufacturing details Printer circuit board is the brain of the computer mouse and therefore, is the first to be manufactured. For mass production jobs of mouse manufacture, PCB is made by a process called “surface mount” PCB in which the computer controlled automatic sequencer places all the electrical and electronic components on the PCB, in proper form, as per the original design. The operation is done entirely by the machine. Holmes , vol 5, page5, 1997; has detailed the process of making a PCB by a method called “Through hole “ design. While each worker adds a number of individual components to the PCB, The bottom portion is then passed through a wave-soldering machine to wash off all the undesired elements using flux. The board is then heated by infrared heat to make it resistant to any thermal shock. After cooling the solder parts, the PCB is tested before the process of encoder mechanism attachment. The encoder mechanism consists of the rubberized ball, the supporting shafts, both spoke wheels and LED detector etc. The plastic parts are made by injection molding process and trimmed to shape by machines, as per the original design. After the encoder mechanism is ready and tested, it is attached to the PCB, using clips or screws. Finally, the board is tested for quality control, as per the design parameters. Outer shell is the major plastic part of the mouse, and is made using injection molding process, followed by trimming of excess plastics and fine shaping the shell The encoder assembly is inserted on the underside of the mouse shell and fitted with the use of screws etc..The electrical cable connected to the mouse is made of electrical wires; shields and rubber cover. There are also two additional molded rubber pieces, called over-molds, which are used to prevent any chance of mouse detachment. The plastic molding and manufacturing process for mouse outer shell is completed in many steps. The driver software should be according to the parameters set by Federal communication system and European communication system, with respect to their governing rules for electrostatic discharge and other related processes. The software thus prepared is stored in diskettes and the mouse with the required software is ready for dispatch now. (6) Quality control for mouse manufacture Quality control jobs involve the testing and review of tooling processes, design of assembly parts. The final mouse shapes are tested as per the computer aided designs, minimizing the chances for any small error. First step in the QA testing is done for the PCB, which is tested for its electronic functions, before the plastic parts are attached to it. The encoder mechanism is tested to check its functionality, before it is assembled to the PCB. The final quality check is for the total function of the mouse, which includes its electronic, electrical functions as well as the mechanical function of the encoder assembly; as well as the driver software tests to meet the necessary regulations. ________________________________________________ Bibliography In-text citation references Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 1, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 23th March 2009 Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 2, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 24th March 2009 Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 3, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 24th March 2009 Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 4, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 25th March 2009 Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 5, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 26th March 2009 Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 6, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 27th March 2009 Nugent Tim (edited by Leslie Gordon), April 2008 A washable computer mouse, paragraph 4 to 7, available at http://machinedesign.com/article/a-washable-computer-mouse-0410 (accessed on 27th. March 2009) Sources used 20 computer mouse designs- 2008- available at http://www.interactivemaster.com/blog--computer--mouse--past--to--present.html figure 11, accessed on 27thMarch, 2009) Nugent Tim (edited by Leslie Gordon), April 2008 A washable computer mouse, paragraph 4 to 7, available at http://machinedesign.com/article/a-washable-computer-mouse-0410 (accessed on 27th. March 2009) Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 1, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 23th March 2009 Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 3, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 23th March 2009 Holmes, Gillian..Vol-5, 1997, “How products are made, computer mouse” Page 5, available at http://findarticles.com/p/articles/mi_gx5205/is_1997/ai_n19124828, accessed on 23th March 2009 Read More