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How does a mouse on a computer work?

How does a mouse work? The current computer mouse incorporates seven technologies. We'll focus on the image sensor and what happens when you move your mouse on a mouse pad. Then, we'll compare gaming mice with 25,000 DPI and a few thousand. Start. Image acquisition system (IAS) of mouse includes infrared LED, optics, and pixel array. LED-generated infrared light illuminates the mouse's surface. Infrared light bounces off the surface, goes through a second lens, and hits a 16-by-40-pixel image sensor. Your mouse misses the pad's color and style.

Light emitted at a shallow angle shows the surface's texture, like a sunset over undulating hills. The hilltops capture and reflect light, but the lowlands remain gloomy. Your eyes may see a uniform black mouse pad or wooden desk, but the image sensor captures a topographically and texturally complex scene. If the surface were totally flat with no defects, the mouse would struggle to work on it, which is why some computer mice don't work well on glass. This 1600-pixel image sensor focuses on a 1/200th-sized area underneath the mouse. The image sensor captures 17,000 photos every second, so even if you move your mouse for a tenth of a second, it will take 1700 photographs. The mouse doesn't save these images; instead, it compares each one to the one taken 59 microseconds before. The microchip uses the difference between the two images to estimate how far and in what direction you moved your mouse in 59 microseconds. Let's explore this idea.

How can a microprocessor discern the change in X and Y between two topographic photos acquired 59 microseconds apart? The two pictures are transferred to the microchip's digital signal processor, or DSP, where cross-correlation is performed. As said, each image is formed of 40 by 40 pixels, and each pixel creates a value between 0 and 4095 that relates to light intensity. We represent values by pixel height. The DSP overlays the second image on the first. Next, the DSP subtracts the second image's pixels from the first, creating a new image. The CPU adjusts the second image while keeping the first still and calculates the difference between them until the resulting image is at a minimum. The amount of shift in position to obtain a minimum resultant image shows us how far the mouse traveled between two successive photographs taken 17000ths of a second apart, measured in pixel counts. 59 microseconds later, another image is acquired, and the CPU runs the same cross-correlation method with the new image shifting and the old image stationary, resulting in another set of data.

The CPU captures more pictures and runs cross-correlation 17 times. Then it adds all the values to find how far the mouse went in 1 millisecond. This combined X and Y change for one millisecond is delivered to a system on a chip, which transfers the information to your computer through USB or Bluetooth [Note: Point to Bluetooth card]. And that's how your mouse calculates every millisecond. Compare gaming mice to non-gaming mice. Apart from the mouse's sharper design, different number and layout of buttons, and LED lights, the biggest distinction is the DPI, or dots per inch. Gaming mice have 12,000 to 25,000 DPI; non-gaming mice have 850 to 4,000 DPI. So, what is DPI? When you move your mouse 1 inch to the right, the number of units it travels on the screen equals dots per inch. A DPI of 2,000 means the mouse pointer moves 2,000 units per inch. What does this have to do with the image sensor and cross-correlation technique we discussed? Say each pixel in this 40 by 40-pixel image sensor is 30 micrometers long and tall, totaling 1.2mm by 1.2mm. If we extrapolated this sensor's pixels to an inch, we'd need 850, yielding a DPI of 850. We must partition each whole or integer pixel using numerous cuts to increase DPI.

In the X and Y directions, divide each pixel by 4. Our 850 DPI sensor now has 4,250 DPI because each pixel has 25 subpixels. If we cut each pixel 29 times, we'd achieve a DPI of 25,500. Note that DPI is a linear unit and PPI is a square unit. So now that we have the whole picture, what happens? A typical method for subdividing full pixels into subpixels is termed interpolation. Here we have 4 whole or integer pixels, each with a value for the light intensity hitting that pixel. As before, the height of each pixel symbolizes the value and an approximation of the surface's texture. Next, we draw a line between the tops of the two groups of pixels in the X direction. Depending on how many subpixels we want, we divide the lines. At each intersection is a new interpolated subpixel. So, adjusting your mouse's DPI changes the number of subdivisions in this interpolation technique.

Here's bilinear interpolation. We draw straight lines between all integer pixels, therefore it's bilinear. A bicubic interpolation uses additional math to generate a smoother topography. Gaming mice broadcast their motions to the computer 1000 times a second, while non-gaming mice provide data 120 times a second. The frame rate of 17,000 is only high when you fast move your mouse; when it's motionless, it scaled down to save battery life. There are several types of mice. In this video, we gave specs for a high-end gaming mouse with a frame rate of 17,000 and a resolution of 25,000 DPI. Typical specs are 4000 to 17,000 fps, 1,000 to 25,000 DPI, 18 by 18 to 40 by 40 pixels, and 100 to 1000 reports per second. Also, we exhibited a mouse that uses an infrared LED for illumination, whereas some mice use a laser, older mice use a red LED, and prehistoric mice use a ball.

That's all I can supply information to you. How does a mouse know when you move it? How Does a Computer Mouse Work? Thanks!

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