What is a scanner and why? Types of scanners

Ministry of General and vocational education Russian Federation

Municipal Educational Institution Lyceum No. 130

Educational area Mathematics

In the office, the scanner can be effectively used to work with both texts and simple images. In this case, you can focus on a black and white model with a resolution of 200-300 dpi. Even a handheld scanner can be useful for entering short documents. At large volumes You should choose a scanner with automatic document feeding. Depending on the complexity of the images entered into the computer, you will need a flatbed scanner with a resolution of 300-600 dpi (with interpolation up to 1200 dpi), with the ability to perceive up to 16.7 million shades of colors - optimal choice for home and office, with a powerful interface (SCSI-2 or USB). In all cases, you need to make sure that the appropriate software is included with the scanner. Don't forget about TWAIN compatibility too.

2. ComputerPress magazine

3. Gookin D. Rathbon E. PC for “dummies” / 4th edition – M.: AST-PRESS, 2001, – 230 p.

4. Evseev G.A., Simonovich S.V. You bought a computer: Complete Guide/ 3rd edition, revised. – M.: INFORCOM-PRESS, 1999, – 464 p.

Application:

Scanner manufacturing technologies

Of all the scanner manufacturing technologies that exist today, we note the four most frequently used. In flatbed scanners made using the relatively new CIS (Contact Image Sensor) technology, each image point opposite the line is recognized by its own sensor and illuminated by its own LED. The advantages of flatbed CIS scanners are their low price, portable size, low power consumption and elegant design. However, practice confirms that most CIS models scan more slowly, and their color rendering and depth of field are slightly worse than those of scanners with a CCD matrix. Flatbed scanners with a CCD matrix (charge-coupled device, or charge-coupled device - CCD) use a lamp with good spectral characteristics as a light source. The type of lamp used, as well as the technology and manufacturing quality of the CCD matrix (sometimes called a CCD line) determine most of the quality characteristics of scanning. The specialized slide scanners mentioned above are designed only for scanning photographic films - negatives and slides, and often only of certain standards. Their CCD matrix is ​​made on the same principle as in digital cameras and video cameras, but due to the fact that its dimensions and power consumption do not play a key role in the production and operation process, slide scanners have a fairly high resolution and a wide range of distinguishable colors and densities. In professional drum scanners, the cost of which is astronomical, the photosensitive element is a photomultiplier tube (PMT), which is similar in operating principle to a cathode intensifying lamp. Thanks to the immobility of the scanning head, precise focusing is ensured, and since each point is scanned separately, noise from the mutual influence of elements is eliminated, as is the case with matrix CCD technology. The original being scanned (slide or negative) is pasted onto a special drum. To prevent the original from being damaged by the extremely bright light (it comes through a fiber optic cable from a halogen lamp), the drum rotates at high speed, gradually moving along the axis of rotation, and for each rotation the head takes only a few points of the image. The majority of the market for both professional and amateur models is occupied by flatbed CCD scanners. Actually, for scanning with acceptable color rendering quality and good detail, choose a home or office scanner limited to this particular group of devices.

A scanner is an office device designed to analyze, read information and transfer it to digital format. Information received on a computer using this device is usually called scans, or scanned copies.

Transfer process graphic or text information V electronic view is called scanning. That is, this equipment performs the reverse of printing - it transfers information from paper to a computer in the form of a file.

The scope of their application is wide, ranging from home use and ending with the creation of printing. It does not allow you to make a copy of a document immediately, but only after processing on a computer, unlike a copier, which immediately prints the result.

What types of scanners are there?

There are enough varieties of scanning devices a large number of. At a minimum, the most basic and modern, seven categories.

Film scanner

They are designed to recognize images captured on the negative, photographic film or slides. Such a device can only scan a transparent image.

This variety must have certain properties. The first is permission. In modern models, this parameter varies from 4000 dpi and above. Therefore, the images obtained when working with them have maximum accuracy.

Second parameter - optical density. The equipment works with films and slides various formats. However, it retains high speed work and quality of the output image.

Depending on the cost, it is equipped with various additional functions . For example, color correction, removing dust and scratches, removing fingerprints and many others.

Laser scanner

This device is widely used for reading various barcodes. This is what allows us to uncontrolled monitoring specially programmed zone. For example, in shops, ticketless transport, for monitoring an object, etc.

This technology allows you to create a 3D model of any product, building or other object without drawings.

Handheld scanners

It is used mainly for working with small amounts of text material. Scanning is carried out by moving the handle slowly across the working area.

Exists many modifications such a scanner:

Wide format scanners

This device is used to scan information from large formats. For example, technical documentation designers, architects, builders, etc. This species is quite mobile. They are easy to move, light weight and compact in size.

One of the varieties wide format scanner – plotters, which are used mainly in offices, design bureaus and the advertising printing industry.

Professional scanners

The fastest type of scanning equipment. Mainly used in educational, scientific, financial and other administrative institutions.

This device is capable of operating in a continuous flow, automatically submit original documents for scanning. It has high quality file processing and the function of editing the resulting images.

Book or planetary scanner

Used for scanning without contact with the original. Most often, it is used to digitize books and images of historical value. It is contactless work that allows you to translate quickly and without damage necessary information into digital format.

Flatbed scanner

The most common and affordable type of digitization equipment. It is used everywhere. Suitable for both home use and work in organizations. Capable scan any documentation up to A4 format.

How does a scanner work and how is it designed?

The standard device is a portable rectangular plastic case with a hinged lid on it. Under this cover is glass surface, on which the sheet to be scanned will be placed.

Inside, the equipment consists of a movable carriage with a mirror system, lens and backlight. When the light from the lamp hits the scanned original, it is reflected and falls on the optics located inside. The resulting electrical impulse contains information about the shape, color and other parameters of the original.

All this information goes into the computer and deciphered special software drivers. After which, on the monitor you see a scanned image that fully matches the document that you loaded into the scanning device.

How to use the scanner

Turn on the equipment. Connect it to your computer using a special cord. Once the device is connected, click the " Start" on standard panel in PC. You need the item “All programs”, then click on “ devices and printers"(or use the search in the system).

Click on " Scan" in the lower left corner of the opened program window, and then select "New Scan" from the toolbar.

A new dialog box will open in which you need to click the list “ Profile" and select the line "Documents". This section will automatically display the default scan settings, you can change them if you wish and preview what the scanned copy will look like. To do this, click “View”.

To start the scanning process, click the " Scan».

Important! Proper work is possible only if the PC has special software drivers, which correspond to the brand of the device. They can be downloaded from the official website or installed from the disk included in the package.

It is worth noting that the procedure is identical for printers with a built-in scanner.

Basic Settings and Precautions

There are several basic important parameters, they are the same for all devices:

• File type. The resolution of the file in which the scanned image is saved on the computer. For example, PDF, JPEG, etc.
• Permission. A parameter characterizing the detail of the resulting digital copy. The larger this property, the more memory is required to store it.
• Scan type. Determines the color depth of the image. There are types such as black and white scanning, grey, color and auto.
• Brightness. Used to adjust image detail. The standard value is 0, the adjustment range is from -50 to 50.
• Contrast. Increasing this setting emphasizes the dark and light areas of the picture. When reduced, on the contrary, they lighten and dim.
• Duplex scanning. Selecting this option will copy both sides of the document.
• Auto-rotate image. Automatically changes the orientation of the resulting scan result.
• Skip blank pages. Eliminate pages without information from the final document.

Precautionary measures using:

1. Use the power source supplied with the device only.
2. Do not leave the equipment plugged in after use.
3. Do not connect the scanner to the computer when its power supply is turned on.
4. If there is a malfunction, do not use the equipment until the technician arrives.
5. Make sure that dirt, water and other substances that can harm the device and render it unusable do not get into the equipment.
6. If your device gets hot, makes strange noises, won't scan, etc., don't try to fix it yourself.

How to use a copier on an MFP

MFP is a device that combines copier, scanner and printer capabilities.

In order to photocopy, the MFP must be connected to an electrical outlet, but it does not have to be connected to a computer.

Place required document under the equipment cover, press the " Start" on the case and the device will give you a sheet with a scanned and printed copy.

It is worth noting that photocopying means obtaining one or more exact copies on paper.

What to do if the scanner does not scan

First of all, see if it is connected to your personal computer. Are the connecting wires damaged?

Try restarting your device and PC. If the scanner still does not work, call your hardware service center.

Scanner- this is a device that, by analyzing an object (usually an image, text), creates a digital copy of the image of the object. The process of obtaining this copy is called scanning.

In 1857, the Florentine abbot Giovanni Caselli invented a device for transmitting images over a distance, later called the pantelegraph. The transmitted image was applied to the drum with conductive ink and read using a needle. In 1902, the German physicist Arthur Korn patented photoelectric scanning technology, which later became known as telefax. Transmitted image was fixed on a transparent rotating drum, a beam of light from a lamp moving along the axis of the drum passed through the original and through a prism and lens located on the axis of the drum hit the selenium photodetector. This technology is still used in drum scanners. Later, with the development of semiconductors, the photodetector was improved, a flatbed scanning method was invented, but the principle of image digitization itself remains almost unchanged.

Main characteristics of scanners

Optical resolution

This is the main characteristic of the scanner. The scanner does not take the entire image, but line by line. A strip of light-sensitive elements moves along the vertical surface of the flatbed scanner and captures the image point by point, line by line. The more photosensitive elements a scanner has, the more points it can remove from each horizontal stripe Images. This is called optical resolution. It is determined by the number of photosensitive elements (photosensors) per horizontal inch of the scanned image. It is usually calculated by the number of dots per inch - dpi (dots per inch). The normal level of resolution is at least 600 dpi; increasing it even further means using expensive optics, expensive photosensitive elements, and increasing scanning time. Processing slides requires more than a high resolution 1200 dpi.

X resolution

This parameter shows the number of pixels in the photosensitive line from which the image is formed. Resolution is one of the main characteristics of a scanner. Most models have an optical scanner resolution of 600 or 1200 dpi (dots per inch). It is enough to obtain a high-quality copy. For professional image work, higher resolution is required.

Y resolution

This parameter is determined by the stroke of the stepper motor and the accuracy of the mechanics. The mechanical resolution of the scanner is significantly higher than the optical resolution of the photo ruler. It is the optical resolution of the photocell line that will determine the overall quality of the scanned image.

Scan speed

The scanning speed depends on the scanning resolution and the size of the original. Typically, manufacturers indicate this parameter for A4 format. Scanning speed can be measured in pages per minute or the time it takes to scan one page. Sometimes measured in the number of lines scanned per second.

Color depth

As a rule, manufacturers indicate two values ​​for color depth - internal depth and external. Internal depth is the bit depth of the ADC (analog-to-digital converter) of the scanner; it indicates how many colors the scanner can distinguish in principle. External depth is the number of colors a scanner can render to a computer. Most models use 24 bits for color reproduction (8 for each color). For standard tasks This is quite enough in the office and at home. But if you're going to use the scanner for serious graphics work, try to find a model with a higher number of bits.

Maximum optical density

The maximum optical density of the scanner is the optical density of the original, which the scanner distinguishes from “complete darkness”. The higher this value, the greater the sensitivity of the scanner and the higher the quality of scanning dark images.

Light source type

Xenon lamps are characterized by short warm-up time, long service life and small in size. Cold cathode fluorescent lamps are cheap to produce and have a long life. Light emitting diodes (LED) are small in size, low power consumption and do not require warm up time. But in terms of color rendering quality, LED scanners are inferior to scanners with fluorescent and xenon lamps.

Scanner sensor type

Scanners and MFPs typically use one of two types of sensors, based on different technologies:

• CIS- Contact Image Sensor / contact image sensor;
• CCD- Charge-Coupled Device / charge-coupled device (CCD).

CIS is a line of photocells that is equal to the width of the surface being scanned. During scanning, it moves under the glass and, line by line, transmits information about the image on the original in the form of an electrical signal. For lighting, LEDs are usually used, which are located in close proximity to the photo ruler on the same movable platform. CIS-based scanners have a simple design, slim body and low weight, which makes the scanner thinner and lighter compared to scanners with CCD sensors. CIS scanners are generally less expensive than CCD scanners. The main disadvantage of CIS is its shallow depth of field.

Photosensor based CCD- this is a specialized analog integrated circuit, consisting of photosensitive photodiodes, made on the basis of silicon, using CCD technology - charge-coupled devices.

The CCD matrix consists of polysilicon separated from the silicon substrate, in which, when voltage is applied through the polysilicon gates, the electrical potentials near the electrodes change. Before exposure, usually by filing certain combination voltage on the electrodes, all previously formed charges are released and all elements are brought into an identical state. Next, the combination of voltages on the electrodes creates a potential well in which electrons formed in a given pixel of the matrix as a result of exposure to light during exposure can accumulate. The more intense the light flux during exposure, the more electrons accumulate in the potential well, and accordingly, the higher the final charge of a given pixel.
After exposure, successive changes in the voltage on the electrodes form a potential distribution in each pixel and next to it, which leads to the flow of charge in a given direction, to the output elements of the matrix.

Types of scanners

• flatbed - the most common type of scanners, as they provide maximum convenience for the user - high quality and acceptable scanning speed. It is a tablet with a scanning mechanism inside under transparent glass.
• manual - they do not have a motor, therefore, the user has to scan the object manually, its only advantage is its low cost and mobility, while it has a lot of disadvantages - low resolution, low speed, narrow scanning band, image distortions are possible, since it will be difficult for the user to move constant speed scanner.
• sheet-pulling (pulling) - a sheet of paper is inserted into the slot and pulled along guide rollers inside the scanner past the lamp. It is smaller in size compared to a flatbed, but can only scan separate sheets, which limits its use mainly to company offices. Many models have a device automatic feeding, allowing you to quickly scan a large number of documents.
• planetary or book scanners - used for scanning books or easily damaged documents. When scanning there is no contact with the scanned object (as in flatbed scanners). Book scanners - designed for scanning bound documents. Scanning is done face up - so your scanning actions are indistinguishable from turning pages during normal reading. This prevents damage and allows the user to see the document while scanning.
• Slide scanners - as the name implies, are used for scanning film slides; they are produced as independent devices or as additional modules to conventional scanners.
• barcode scanners - small, compact models for scanning product barcodes in stores.

Operating principle

The object to be scanned is placed on the glass of the tablet with the surface to be scanned down. Under the glass there is a movable lamp, the movement of which is controlled by a stepper motor. The light reflected from the object, through a system of mirrors, hits the sensitive matrix, then to the ADC and is transmitted to the computer. For each step of the engine, a strip of the object is scanned, which are then combined by software into a common image.

The image is always scanned in RAW format- and then converted to normal graphic format using the current settings for brightness, contrast, etc. This conversion is carried out either in the scanner itself or in the computer, depending on the model of the particular scanner. The parameters and quality of RAW data are affected by scanner hardware settings such as sensor exposure time, white and black calibration levels, etc.

Scanners are primarily designed to convert information that is on paper into electronic format.

Main types of scanners:

• Tablets.
• Manual.
• Leafy.
• Book scanners.
• Planetary scanners.
• Drum scanners.
• Slide scanners.
• Barcode scanners.
• 3D scanners.
• Ultrasound scanners.

Agree, it is not easy for a user to understand such diversity. Now let’s briefly look at what the listed types of scanners are and their characteristics.

Flatbed scanners

Flatbed scanners are the most common and user-friendly. Flatbed scanners are capable of providing high quality and sufficient good speed scanning. By appearance resemble a tablet.

If you open the scanner cover, there is transparent glass inside and underneath it is the scanning mechanism. The object to be scanned is placed on the glass with the scanned surface facing down. The lid must be closed.

Handheld scanners

Handheld scanners do not have a motor. The user has to move the object that needs to be scanned manually. The only advantage of such scanners is their low cost. But hand scanners have a lot of disadvantages:

• Low resolution;
• Low scanning quality (image distortions are possible since moving the scanner manually at a constant speed is quite problematic);
• Low speed;

Sheet scanners

In sheet-fed scanners, a sheet of paper must be inserted into a slot and pulled along guide rollers inside the scanner. Compared to flatbed scanners, such scanners are smaller and can scan only individual sheets. Some models have an automatic feeder.

Book scanners

Designed for scanning bound documents. Unlike flatbed scanners, scanning is done face up. Book scanners provide excellent scanning quality and are even able to smooth out distortions that are inevitable when a book is folded.

Planetary scanners

In such scanners there is no contact with the object being scanned, so they are intended primarily for documents that are easily damaged. They can also be used for scanning books.

Drum scanners

Provide very high scanning quality. Used in printing.

Slide scanners

Designed for scanning film slides.

Barcode scanners

Designed for use in stores to scan product barcodes.

3D scanners

Designed for scanning real physical objects. In the process of such scanning, a real object is converted into digital form and a three-dimensional computer model of the object is obtained.

Ultrasound scanners (ultrasound scanners)

Intended exclusively for medical use for the study of internal organs.

Introduction

1. Types of scanners

2. Scanner characteristics

3. Software

4. Manufacturers

Conclusion

Literature

INTRODUCTION

Scanner(English scanner) are text or graphic information to the computer by converting it to digital view for subsequent use, processing, storage or output.

In 1857, the Florentine abbot Giovanni Caselli invented a device for transmitting images over a distance, later called pantelegraph. The transmitted image was applied to the drum with conductive ink and read using a needle.

In 1902, the German physicist Arthur Korn patented photoelectric scanning technology, which later became known as telefax. The transmitted image was fixed on a transparent rotating drum, a beam of light from a lamp moving along the axis of the drum passed through the original and through a prism and lens located on the axis of the drum hit the selenium photodetector. This technology is still used in drum scanners.

Later, with the development of semiconductors, the photodetector was improved, a flatbed scanning method was invented, but the principle of image digitization itself remains almost unchanged.

1. TYPES OF SCANNERS

Depending on the method of scanning an object and the scanning objects themselves, there are the following types of scanners:

Flatbed scanners are the most common type of scanners, as they provide maximum user convenience - high quality and acceptable scanning speed. It is a tablet with a scanning mechanism inside under transparent glass.

The object to be scanned is placed on the glass of the tablet with the surface to be scanned down. Under the glass there is a movable lamp, the movement of which is controlled by a stepper motor.

Light reflected from an object enters a sensitive matrix through a system of mirrors. The receiving element converts the light level into a voltage level. Further, after possible correction and processing, analog signal goes to an analog-to-digital converter (ADC). From the ADC, the information comes out in binary form and, after processing in the scanner controller, through the interface with the computer, it enters the scanner driver - usually this is the so-called TWAIN module, with which application programs already interact.

For each step of the engine, a strip of the object is scanned, which are then combined by software into a common image.

Used as a linear light source Fluorescent Lamp with a light spectrum close to daylight, and a CCD line (charge-coupled device) is used as a receiver.

Manual - they do not have a motor, therefore, the user has to scan the object manually, its only advantage is its low cost and mobility, while it has a lot of disadvantages - low resolution, low operating speed, narrow scanning band (up to 10 cm), possible skewed images because it will be difficult for the user to move the scanner at a constant speed.

Sheet-pulling - a sheet of paper is inserted into a slot and pulled along guide rollers inside the scanner past the lamp. It is smaller in size compared to a flatbed, but can only scan individual sheets, which limits its use mainly to corporate offices. Many models have an automatic feeder, which allows you to quickly scan a large number of documents.

Book scanners - designed for scanning bound documents. Modern models Professional scanners can significantly increase the safety of documents in archives, thanks to very delicate handling of the originals. Scanning is done face up. The software used in book scanners allows you to eliminate defects, smooth out distortions, and edit the resulting scanned pages. Book scanners have a unique book de-crease function, which ensures excellent quality of the scanned (or printed) image.

Planetary scanners - used for scanning books or easily damaged documents. When scanning there is no contact with the scanned object (as in flatbed scanners).

Drum scanners - Drum scanners, which are significantly superior in light sensitivity to consumer tablet devices, are used exclusively in printing, where high-quality reproduction of professional photographs is required. The resolution of such scanners is usually 8000-11000 dpi or more.

In drum scanners, originals are placed on the inside or outside (depending on the model) side of a transparent drum. After mounting the original, the drum is set in motion. One line of pixels is read per revolution, so the scanning process is very similar to the operation of a screw-cutting lathe. A focused beam of light passing through a slide (or reflected from an opaque original) hits a splitting system (prism or block of mirrors) and, through three light filters, hits photosensitive elements - photomultipliers.

Halogen or xenon lamps with a power of 30-75 W are used as a point light source, because they combine high radiation intensity with a fairly uniform power distribution over the entire range of the radiation spectrum.

Slide scanners - as the name implies, are used for scanning film slides; they are produced as independent devices or as additional modules to conventional scanners.

Barcode scanners are small, compact models for scanning product barcodes in stores.

3 D -scanners- devices that analyze a physical object and, using the obtained data, create a 3D model. They are used for engineering analysis, control, design, games and entertainment (creating digital models characters), in medicine and other fields.

Three-dimensional or 3D scanning is the process of translating the physical form real object in digital form, i.e. obtaining three-dimensional computer model object.

In order for the scanner to “link” to the object being scanned, special index anchor marks are glued to the object before scanning. The combination of these marks forms a unique coordinate system associated with the object in which the surface is constructed. In the case of an optical scanner, these points are used to glue individual scans together.

All shiny, mirror or transparent surfaces of the object are coated with an anti-reflective compound, creating a white matte surface suitable for optical or laser 3D scanning.

The output from the scanner is a triangular polygonal model of the object.

3D scanners are divided into two types based on the scanning method:

· Contact, this method is based on direct contact of the scanner with the object under study.

Contact 3D scanners are built on the principle of tracing a model with a special, highly sensitive probe; with the help of it, the three-dimensional coordinates of the scanned model are transferred to the computer.

· Contactless.

Non-contact devices can in turn be divided into two separate categories:

· Active scanners

· Passive scanners

Active scanners emit some directed waves (light, laser beam, ultrasound or x-rays) onto an object and detect their reflection for analysis.

Passive scanners do not emit anything at the object, but instead rely on detecting reflected ambient radiation. Most scanners of this type detect visible light, which is readily available ambient radiation.

Ultrasound scanners(ultrasound scanners) – used in medicine to study internal human organs.

The operation of an ultrasound scanner is based on the fact that ultrasonic vibrations, when propagating, obey the laws of geometric optics. Any medium, including body tissues, prevents the propagation of ultrasound, that is, it has different acoustic resistance, the value of which depends on their density and the speed of ultrasound.

Having reached the boundary of two media with different acoustic resistance, the beam of ultrasonic waves undergoes significant changes: one part of it continues to propagate in the new medium, being absorbed to one degree or another by it, the other is reflected. The reflection coefficient depends on the difference in the acoustic resistance of tissues adjacent to each other: the greater this difference, the greater the reflection and, naturally, the greater the amplitude of the recorded signal, which means the lighter and brighter it will appear on the device screen. A complete reflector is the boundary between tissue and air.

2. SCANNER CHARACTERISTICS:

Original type. Scanning can be done in transmitted light (for originals on a transparent backing) or reflected light (for originals on an opaque backing). Scanning negatives is particularly challenging because the process is not simply about inverting the color gradations from negative to positive. To accurately digitize color in negatives, the scanner must compensate for the color photographic veil on the original. There are several ways to solve this problem: hardware processing, software algorithms for transitioning from negative to positive, or lookup tables for specific types of film.