2020-10-11
525
I. Read and translate the text.
The touch screen is, in a sense, the ultimate in simplicity for the computer user: touch the screen with your finger and something happens. As with the bit pad, different regions of the screen are assigned to different actions and are visually indicated by shape, colour, and text. The visitor information systems at Epcot (E xperimental P rototype C ommunity o f T omorrow) theme park at Walt Disney World Resort use touch screens.
The principle of the touch screen is electrical; the screen is fabricated with conductive and insulating layers in such a way that when a human finger presses on the screen (which is slightly deformable), an electrical connection is made. Making the screen sensitive to pressure rather than simply to touch improves its robustness under dirty conditions whether industrial grime or chocolate sauce on children’shands. One problem with the touch screen is that the human finger is a rather imprecise pointing device compared to a light pen or mouse. This limits the number of choices that can be displayed on a normal-sized computer screen at one time and forces the programmer to deal with questions concerning what happens if someone presses partly inside and partly outside a region. These problems have limited touch screen applications in industry.
II.Answer these questions.
1. What is a touch screen? 2. What is the principle of a touch screen? 3. Why is the screen made sensitive to pressure and not to touch? 4. What is the problem with the screen touch? 5. Why are touch screen applications limited?
III. Speak on the principle of the touch screen.
Lesson 5. Scanner
I. Before reading the text discuss how many ways there are of capturing an image on a computer.
II. Read the text and see how many things from your list are mentioned.
III. Read the text again and answer these questions.
1. Which device is used to input text and graphic images from a printed page?
2. How does a scanner send information to the computer?
3. Why is text scanning difficult?
4. In addition to flatbed (or desktop) scanners there are also handheld scanners, drum scanners, film (“slide” or negative) scanners and camera scanners. Do you know what they are used for?
A more recent and more widely applicable method of entering graphical information into computers is the optical scanner. A scannertakes a black and white paper original and represents it as a set of ones and zeros that correspond to little black and white squares. This kind of image is often called bit-mapped, since the information in the drawing has been “mapped” into a sequence of black and white squares or binary bits. A scanner “sees” images and converts the printed text or pictures into electronic codes that can be understood by the computer. With a flatbed colour scanner, the paper with the images is placed face down on a glass screen, as with a photocopier. Beneath the glass are the lighting and measurement devices. Once the scanner is activated, it reads the image as a series of dots and then generates the digitized image that is sent to the computer and stored as a file.
The scanner operates by using three rotating lamps, each of which has a different coloured filter: red, green and blue. The resulting three separate images are combined into one by appropriate software.
A difficulty with scanning technology is that the resulting image takes up a great deal of disk space if high resolution is desired. Text scanning is even more difficult, since the computer not only has to read in the image but must also decide whether the shape it is seeing is an A, a B, or whatever. Different types of fonts or poor quality printing sharply reduce the performance of text scanners, but the technology is developing.
IV. Complete the following sentences.
1. The technology used in scanners is similar to that used in a ____. 2. The scanned image is sent to the _____, where you can manipulate it. 3. To scan the text, you need special ______. 4. Flatbed scanners can scan ____.
V. What other ways of capturing an image on a computer do you know?
VI. What does a digital camera do?
VII. What does the term “camcoder” stand for? What does a camcoder do?
VIII. What do you know about web cameras (webcams)?
