What is an optical mouse?

An optical mouse is an optical mouse

The optical mouse passes through the LED light at the bottom. The light shines on the desktop at an angle of about 30 degrees, illuminating the shadows produced by the rough surface, and then passes through The refraction of the plane is fed back to the sensor through another lens. When the mouse moves, the imaging sensor records continuous patterns, and then uses a "Digital Signal Processor" (DSP) to compare and analyze each picture before and after to determine the direction and displacement of the mouse movement, thereby determining the position of the mouse on the screen. The coordinate value on the mouse is then passed to the Micro Controller Unit of the mouse through SPI. After the mouse's processor processes these values, it passes them to the computer host.

Table of contents

Introduction

Development history

The working principle of the optical mouse

Technical parameters

Main manufacturers

[Appendix: Several issues in using optical mice]

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Introduction

The first true optical mouse was launched by Agilent in 1999. This mouse uses a revolutionary optical positioning sensor, which continuously "takes pictures" of the contact interface during the movement of the mouse, and compares the front and rear images to obtain the specific displacement and speed of the mouse.

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Development history

In 1963, the world's first mouse prototype was born at the Stanford University Research Institute in California, USA. Its prototype was designed by Douglas Created by Dr. Englebart and developed by his chief engineer Bill English, it became the world's first mouse. Dr. Englebart's original intention of designing the mouse was to replace the cumbersome instructions on the keyboard, making computer operation more convenient and faster, and laying the first cornerstone for the popularization of computers in the future.

In 1971, (Xerox) Palo Alto Research Center signed a usage agreement with the Stanford University Research Institute, allowing Xerox to use the mouse technology. Since then, mouse technology has gradually developed. , they launched the world's first mechanical scroll mouse called "Alto Mouse" in 1972. Today's mechanical scroll technology largely comes from the contribution of Xerox's Palo Alto Research Center.

With the development of technology and market demand, the Palo Alto Research Center launched the first optical mouse in 1985. However, this optical mouse requires a special gridded mouse pad to function properly. Used, so it can only be said to be the prototype of an optical mouse.

Finally in 1999, Agilent launched a revolutionary optical positioning sensor. It continuously "photographed" the contact interface during the movement of the mouse, compared the before and after images, and obtained the mouse positioning sensor. specific displacement and velocity. The most important thing is that it can operate on most surfaces and become a true optical mouse.

Optical mouse composition

An optical mouse usually consists of the following parts: optical sensor, optical lens, light-emitting diode, interface microprocessor, touch buttons, scroll wheel, connection, PS/2 or USB interface, housing, etc. The following are introduced respectively:

Optical sensor

The optical sensor is the core of the optical mouse. Currently, there are only three manufacturers that can produce optical sensors: Agilent, Microsoft and Logitech. Among them, Agilent's optical sensors are widely used. Except for all Microsoft and some Logitech optical mice, other optical mice basically use Agilent's optical sensors.

Optical mouse control chip

The control chip is responsible for coordinating the work of various components in the optical mouse, communicating with external circuits (bridging), and transmitting and receiving various signals. We can understand it as the "housekeeper" of the optical mouse.

There is a very important concept here that everyone should know, which is the impact of dpi on mouse positioning. DPI is used to measure the number of points that can be detected per inch of mouse movement. The smaller the DPI, the fewer the points used for positioning, and the lower the positioning accuracy; the larger the DPI, the more points used for positioning, and the lower the positioning accuracy. high.

Normally, the scanning accuracy of traditional mechanical mice is below 200dpi, while the optical mouse can reach 400 or even 800dpi. This is the main reason why the optical mouse can easily surpass the mechanical mouse in positioning accuracy. reason.

Optical lens assembly

The optical lens assembly is placed at the bottom of the optical mouse. It can be clearly seen from Figure 5 that the optical lens assembly consists of a prism mirror and a circular Made up of shaped lenses. Among them, the prism is responsible for transmitting the light emitted by the light-emitting diode to the bottom of the mouse and illuminating it.

The circular lens is equivalent to the lens of a camera. This lens is responsible for transmitting the illuminated bottom image of the mouse to the small hole at the bottom of the optical sensor. By looking at the back shell of the optical mouse, we can see that the circular lens is very much like a camera. Through the test, the author concluded that whether blocking the light path of the prism mirror or the circular lens will immediately cause the optical mouse to become "blind" .

The result is that the optical mouse cannot be positioned, which shows the importance of the optical lens assembly.

Light-emitting diode

The optical sensor needs to continuously "take pictures" of the bottom of the mouse that lacks light, so the support of a "photographic light" is naturally indispensable. Otherwise, the image taken from the bottom of the mouse will be dark. Dark images cannot be compared, and of course optical positioning cannot be performed. Usually, the light-emitting diodes used in optical mice are red (some are blue) and are highly bright (in order to obtain sufficient illumination). Part of the red light emitted by the light-emitting diode illuminates the bottom of the mouse through the optical lens (the prism) at the bottom of the mouse; the other part is transmitted directly to the front of the optical sensor. In one sentence, the function of the light-emitting diode is to generate the light source required for the operation of the optical mouse.

Touch buttons

It is unimaginable to have a mouse without buttons, so even an ordinary optical mouse will have at least two touch buttons. Founder's optical mouse has three touch buttons welded on its PCB. In addition to the left and right buttons, the middle button is assigned to the page turning wheel. Advanced mice usually have two page turning wheels, X and Y, but most optical mice only have one page turning wheel like this Founder optical mouse. When the page turning wheel scrolls up and down, the "document" or "webpage" being viewed will scroll up and down. When the scroll wheel is pressed, the "middle button" on the PCB will work. Note: The actions generated by the "middle key" can be defined by the user according to their own needs. When we remove the page-turning roller, we can see that there is a pair of photoelectric "transmitting/receiving" devices "hidden" in the position of the roller. There is a grid on the "roller". Because the grid can "block" the light path of the pair of photoelectric "transmitting/receiving" devices at intervals, a page turning pulse signal can be generated. This pulse signal is transmitted to the Windows operation through the control chip. The system can generate page turning action.

In addition to the above, optical mice also include connecting cables, PS/2 or USB interfaces, shells, etc.

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The working principle of the optical mouse

[1] The biggest difference between the optical mouse and the mechanical mouse is the different positioning methods.

The working principle of the optical mouse is: there is a light-emitting diode inside the optical mouse, and the light emitted by the light-emitting diode illuminates the bottom surface of the optical mouse (this is why the bottom of the mouse always glows). Then a part of the light reflected back from the bottom surface of the optical mouse passes through a set of optical lenses and is transmitted to a light sensing device (micro imager) for imaging. In this way, when the optical mouse moves, its movement trajectory will be recorded as a set of coherent images shot at high speed. Finally, a special image analysis chip (DSP, digital microprocessor) inside the optical mouse is used to analyze and process a series of images taken on the moving trajectory. By analyzing the changes in the position of the feature points on these images, the mouse is judged. Movement direction and movement distance to complete cursor positioning.

The principle of the second-generation optical mouse is actually very simple: it uses a photoeye technology, that is, digital photoelectric technology, which uses infrared rays to illuminate the surface of the object where the mouse is located, and then at regular intervals Just take a snapshot (a few milliseconds), and then analyze and process the characteristics of the two pictures to determine the movement direction and value of the coordinates. Since the picture needs to be scanned to determine the displacement of the mouse, the frequency of this scan has become an important parameter for measuring the optical mouse. This Flying Fox mouse uses BenQ's unique "micro-optical positioning system", which can emit 1,500 photosensitive signals per second to scan the surface of an object. After obtaining the image, it uses a DSP digital signal processor to compare each subtle movement direction with the mouse. Distances are returned quickly and accurately. Flying Fox also has a resolution of up to 800DPI, which makes the cursor positioning more accurate. The high-speed sensor can also avoid pointer jitter and irregular movement, improving aiming accuracy. Let us be handy in various operating environments.

The mouse's optical sensor scans the surface on which the mouse is placed and captures images at a frequency of 1500 times/second for comparison to determine the position of the mouse. The number of scans of the optical chip used by traditional optical mice is generally 1,500 times/second (the so-called number of scans, that is, the number of images collected and processed by the optical positioning chip per second), and can only track a maximum movement speed of 14 to 18 inches/second. If the mouse movement speed exceeds this range, the cursor may not be positioned accurately. When users use computers, the mouse movement speed can reach up to 30 inches per second. Especially in FPS games such as CS, this will cause the problem of the mouse suddenly losing control as mentioned above.

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Technical Parameters

CPI

The imaging principle of the optical engine is actually microphotography, and its CPI level is Equivalent to magnified clarity of photographic detail. It only depends on the magnification of the optical component. The resolution is usually expressed in DPI (dots per inch), which can measure the accuracy of the mouse. Most optical mice on the market have 400 CPI.

Sampling rate

This is a unique technical parameter of the optical mouse. It represents the number of times the CMOS sensor "shoots" the sampling surface per second and the corresponding processing power of the DSP chip per second. .

CMOS pixel number

It is necessary to ensure that when moving the mouse at high speed, two consecutive samples will not have the same sampling point. In addition to accelerating the scanning frequency, the size of the CMOS can also be increased. As the number of CMOS pixels increases, of course, more feature points can be used. Improves mouse recognition of fine, repetitive surfaces.

Pixel processing capability

The CMOS size and DSP processing capability are combined into "pixel processing capability. This indicator represents the computing performance of the optical engine's comprehensive sampling.

Maximum speed and maximum acceleration

Combining pixel processing capabilities with CPI parameters can derive two parameters: maximum speed and maximum acceleration. When a human hand uses a mouse, the maximum moving speed is about 30 inches/inch. seconds, which is the maximum acceleration that the mouse can achieve through DSP calculations while ensuring accuracy

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Main manufacturers

Logitech< /p>

Logitech was originally an OEM manufacturer. Most of the world's largest PC manufacturers are Logitech's OEM customers. Logitech's quality control standards are used to mass produce products and provide global distribution and logistics services at retail. Expanding product lines and market share in the field, as more and more consumers add personalized and powerful peripherals to their PCs and gain more freedom of use through wireless desktops, the current consumer trends have greatly improved. This has promoted the diversification and comprehensiveness of Logitech's products. Consumers also purchase auxiliary equipment designed for new applications or specific purposes such as gaming, multimedia or online audio-visual communication. In addition, Logitech's retail business extends beyond PC-based products. The platform includes personal peripherals such as game consoles, portable music players, mobile phones and home entertainment systems. Product lines include keyboards, webcams, headsets, speakers, headphones, game controllers and remote controls. 2008. On March 15, the internationally renowned peripherals giant Logitech announced that it would acquire Ultimate Ears for US$34 million.

Shuangfeiyan

Shuangfeiyan, a well-known domestic peripherals brand, has been around since its birth in 1987. We have fully cooperated with Taiwan's A4TECH, conducted production testing entirely in accordance with international quality control standards, established a complete production and quality management system, and passed the ISO9001 system certification by Germany's TUV.

The main products include mice, keyboards, cameras, speakers, chassis, headphones, etc.

Shuangfeiyan, a well-known domestic peripheral brand, fully cooperates with Taiwan's A4TECH, which was born in 1987, and is completely based on international standards. We conduct production testing according to quality control standards, established a complete production and quality management system, and passed the ISO9001 system certification by German TUV.

rapoo, wireless. Peripheral technology experts are committed to providing high-performance, high-quality computer peripheral products to PC users around the world. As early as 1996, the founder of Rapoo had already carried out professional wireless peripheral technology research and product development: in August 1996. In September, it successfully developed a radio frequency wireless mouse and obtained a patent; in 2001, the world's first photoelectric wireless mouse with human body sensing power-saving mode was born in Rapoo Studio. It was the world's smallest power-consuming photoelectric wireless mouse at that time; Since 2005, Rapoo has launched the third-generation wireless technology. The wireless laser multimedia mouse series, which integrates 2.4G wireless technology, laser technology, multimedia control center and other functions, has been born since then. It has won multiple patents and is known as the new generation of wireless mouse. The "pinnacle" of the mouse. With its strong R&D strength, Rapoo products have made a huge splash at previous Cebit in Hannover and CES electronics shows in the United States, and won praise from the industry.

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[Appendix: Several issues in the use of optical mice]

Everyone usually finds the following when using an optical mouse Problem: The mouse cannot work properly on smooth surfaces such as glass, metal, or surfaces of certain special colors. The cursor is stagnant, trembling, drifting or unresponsive, or even the cursor is lost. These two problems cannot be completely solved until now. So why does this happen? The fundamental reason lies in the limitations of the innate principle of the optical mouse. We may wish to conduct further analysis on this.

We know that the optical engine of the optical mouse determines the direction of the cursor by receiving feedback images. If the moving surface is too smooth, it may not be able to generate enough diffuse reflection light, so the reflection received by the sensor The light intensity is very weak, making it impossible for the positioning chip to determine, causing the mouse to work abnormally. However, the glass mouse pads and metal mouse pads currently on the market do not have smooth surfaces, but are frosted. The diffuse emission conditions are good, but there are still many optical mouse products that cannot work on them.

This involves another reason. We know that the positioning chip determines the position information of the cursor by comparing the differences in feature points on adjacent image matrices, and the frosted surfaces of some glass mouse pads and metal mouse pads are quite fine. The surface is highly consistent. If it is a traditional optical mouse, it can be moved quickly and easily, but this is not the case for optical mice. The highly consistent surface causes the difference between different feature points to be too small. The sensor cannot reflect the difference after converting it into a digital signal. Naturally, it is difficult for the positioning chip to perform comparison processing, resulting in a result where the mouse is at a loss. Naturally, you cannot expect it to be able to do so. It's working normally. However, sensor manufacturers can alleviate this problem by increasing the size of the CMOS photoreceptor. The larger the size of the photoreceptor, the higher the resolution accuracy of the captured image. The greater the number of feature points, the more feature points the positioning chip can compare, so that more accurate judgments can be made. Of course, the increase in sensor size means that more information needs to be processed, and the computing power of the positioning chip must also be improved simultaneously. The current representative of this kind of technical solution is Agilent Technology's "MX Optical Positioning Engine". The sensor specification of an ordinary mouse is 22×22 pixels, while the "MX Optical Positioning Engine" increases to 30×30 pixels, which can ingest more information. Volume increased by 80%.

The answer to the problem of an optical mouse not working properly on certain colored surfaces (also known as "color blindness") is similar to the one above. The optical engine achieves cursor positioning by capturing images and comparing the differences. To capture images, the sensor is required to capture reflected light with a certain intensity and uniform diffuse reflection. However, most sensors can only sense certain wavelengths of color light and are incapable of detecting color light in other wavelength bands. If the surface of the mouse pad happens to be able to absorb a large amount of the color light that the sensor can sense, resulting in insufficient intensity of the color light reflected back, and the sensor cannot sense effectively, it will naturally be impossible to calculate the specific position of the cursor. However, "color blindness" is not a defect. Users only need to choose a mouse pad with a suitable color. If the mouse manufacturers work hard to solve this problem, I am afraid it will cost a lot.