Computer Mice
By: Araf Ani
Table on Contents:
Picture from: https://unsplash.com/photos/Ox7mSmsljkc
Ani, Araf 9/24/22
Technical Description: Computer Mouse Writing for Engineers
The computer mouse is one of the most important tools a person can have when operating a computer. Every who has ever used a computer has used or at least has seen a computer mouse. The purpose of this document will be to explain to you a summarized history of the computer mouse and how a computer mouse works.
There are two different types of computer mice. There is the modern optical variant, almost everyone today uses this type of mouse. Then there is the old ball style variant, this was the original computer mouse and can be seen in older models of apple or Microsoft computers.
The first ever type of computer mouse was the ball type. The actual trackball inside the mouse has been around since post-World War II. Post-World War II, 1946, Ralph Benjamin was working from the British Royal Scientific Service. Benjamin was working on a sort of tracking system for the military to use to aim at enemy aircraft. Benjamin invented the fire-control radar plotting system called Comprehensive Display System (CDS). His project basically used analogue computers to calculate where an aircraft would be flying based on user input from a joystick. This joystick felt clunky to Benjamin, so he had to find a way to get a smoother feeling controller. So, he invented what we call a “roller ball”, to get a smoother controller. Benjamin patented this device in 1947, however only a prototype was ever made. After that, this device was kept a military secret.
The first real computer mouse to be invented was created by Douglas Engelbart of Stanford Research Institution (SRI). During the early 1960s, Engelbart already has established his own research lab at Stanford Research Institution. Engelbart was working on ways for humans to use and interact with computers. Engelbart was thinking how he could use the implementation of x and y coordinate data to interact with a computer. In 1964, Bill English joined up with Douglas Engelbart at Stanford Research Institution. Together, they created the very first prototype of the computer mouse. They didn’t call it a mouse back then; it was named the “X-Y Position Indicator for a Display System”. The prototype was first mentioned to the public in 1965. SRI filed for a patent on the idea in 1967 and the patent was issued in 1970. The first demonstration of the mouse was in 1968. Engelbart demonstrated the mouse on December 9th, 1968. This demonstration has had such a big impact to the computer that it is known today as “The Mother of All Demos”.
The Engelbart mouse
1968
Image taken from: https://www.smithsonianmag.com/smart-news/the-creator-of-the-computer-mouse-never-received-any-royalties-7133825/
How does a computer mouse work?
When the mouse is pushed along a surface and moves, the ball inside of the mouse rolls under its own weight and applies pressure to two thin wheels, figure 1, items 6 and 7. These two wheels detect the movements of the mouse. One wheel detects the x-axis movement, and one wheel detects the y-axis movement. These two combine to show you movement on your cursor in relation to your mouse movement.
With this idea in mind, if when the mouse moves straight down, then only the y-axis wheel will move. Similarly, if the mouse moves right, then only the x-axis wheel will move. If the mouse moves at an angle, then both wheels will turn. The mouse measures how far you move your mouse by using a gear. The gear can be found in figure 2. When the mouse moves, gears spin, there are little holes on the gear. Light passes through the holes, and depending how much the gear spins, is how far your mouse understands it moved. The mouse calculates all this with a microchip inside the mouse. This microchip can be found in figure 1, item 5.
The main drawback to this mouse would be the surface you are using it on. The surface cannot be dirty, and it must be smooth/flat. If the surface has unusual properties, then it can mess up the way the mouse reads direction. This causes the mouse to think it is moving erratically, something you don’t want.
Figure 1:
2. Switch for middle button.
3. Switch for right button.
4. Old-style connection to PS/2 socket on computer.
5. Chip turns back-and-forth (analog) mouse movements into numeric (digital) signals computer can understand.
6. X-axis wheel turns when you move mouse left and right.
7. Y-axis wheel turns when you move mouse up and down.
8. Heavy rubber wheel.
9. Spring presses rubber ball firmly against X- and Y-axis wheels so they register movements properly.
10. Electrolytic capacitor
11. Resistors.
Source: https://www.explainthatstuff.com/computermouse.html#how-ball-works
An optical mouse works by using LED lights instead of a roller ball. This mouse maybe what you are using right now. The optical mouse is much common these days, compared to the ball roller mouse. The optical mouse, in laymen’s terms, shines a red light onto whatever surface you are on, this would be figure 4 item 1. This light then gets reflected back to the photocell on the mouse, which is right next to the light emitter. The photocell has a magnifier on it, so it can more accurately follow your movements, this can be seen in figure 4 item 3. The mouse reads the movements by seeing how the light it emits moves around, this is seen in figure 4 item 3. It looks at the movement of this light and shows similar movement in the cursor on your computer. This type of mouse is a lot simpler to understand, compared to the ball type mouse. It just emits a light, sees how that light moves, and translates that movement onto the computer. To see this in action, check out figure 3.
The main drawback to using a optical type mouse is that if the light sensor gets dirty, it will be unusable. The light emitted from the bottom is how the mouse calculates movement. If that is removed, then the mouse is no more than a paper weight. The main benefit to using a optical mouse is that it can be used on any non-dirty surface. Unluck the roller ball type, the optical mouse can be used on non-flat surfaces.
Figure 4:
1. An LED at the back generates red light and shines it horizontally, from the back of the mouse toward the front (from the left to the right of this photo).
2. A plastic light guide channels the light from the LED at an angle, down onto the desk.
3. A light-detector chip measures light reflected back up from the desk, converting the analog movements of your hand into digital signals that can be sent to your computer.
4. The scroll wheel at the front of the mouse is mounted on a switch mechanism that detects both how much it’s rotated and whether you’ve pressed it (it functions like the central button of a conventional mouse). Rotations of the scroll wheel can be detected in a variety of different ways. Some mice use potentiometers (broadly, variable resistors), similar to the volume control on a radio but able to turn around multiple times. Others use various kinds of rotary switches or optical (rotary) encoders to convert analog wheel movements to digital signals.
5. A microswitch detects when you press the right mouse button. There’s an identical switch on the other side to detect the left mouse button.
6. The USB cable connection carries digital information from the mouse to your computer.
If people were to buy a laptop, they would not be expected to own a mouse. People with arthritis or other hand problems may not be able to use a mouse. For these reasons, engineers have thought of another type of way to move a cursor on a screen. This type of tool is something called a trackpad.
Think of a trackpad as a map. The trackpad is linked directly to the screen. When a user presses down on a trackpad, that part is directly linked to the cursor on screen. When the user moves their finger, the trackpad sees how the finger moves and traces it onto the screen. This is the general gist of how a trackpad works.
Trackpad on a common laptop
Mice are one of the most important parts of a computer. Without a mouse or trackpad, the user would have no way to interact with a computer. The mouse is needed to use a computer. The ball roller mouse and the optical mouse are the most common types of mice. While the optical mouse uses LED lights instead. The optical mouse can be more accurate and is what is used with today’s computers.
Overall, during this whole process of writing this research paper, I learned a lot about citing and how a computer mouse works. I will be honest; I had no idea how a computer mouse worked before this assignment. I had to read a lot about the history of the mouse and also how a mouse works with a computer. I have never used a ball type mouse, so I didn’t even know they existed. I always used an optical type mouse. It was nice to learn about the roller ball type, which type of mouse have you used Professor? I will keep trying to get my citations better and also try to paraphrase more often now.
For my next assignment, I will use my citation skills more and I will paraphrase instead of using direct quotes. I also saw that I used words like “when you do x” instead of “when the computer mouse does x”. I will try to refrain from writing like this in the future. I agree that it sounds better when I do not refer to the reader specifically. I will also use my knowledge from this assignment in my career field. I am going to be a computer engineer, so I will need to know how a computer and all it’s parts work.
Website 1: https://www.explainthatstuff.com/computermouse.html#how-Cball-works
Author: Chris Woodford
Last updated: March 1, 2022.
Website 2: https://en.wikipedia.org/wiki/Computer_mouse#History
Author: SRI International
Website 4: https://www.techwalla.com/articles/how-do-touchpads-work
Author: Angie Briggs
This entry is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license.
