Area Charge-Coupled Devices

Three basic architectures (Fig.18.2) are used in area CCDs. The simplest is the full-frame CCD, consisting of an imaging area separated from a horizontal CCD shift register by a transfer gate.

Figure 18.2. Basic architectures used in CCDs

The requirement for an external shutter is greatly reduced in the frame-transfer CCD sensor by the provision of a light-shielded storage section into which the entire two-dimensional image charge is shifted at a much higher rate (limited primarily by CTE considerations) than is possible in a full-frame CCD. Image smear is virtually eliminated by the interline-transfer (ILT) architecture in which each column of photosites has an adjacent light-shielded vertical CCD shift register into which the charge is transferred by a transfer pulse. This approach makes it easy to implement exposure control and achieve short integration times, but it introduces dead space between the active pixels, reducing the sensitivity of the image sensing area and increasing aliasing effects compared with frame-transfer sensors.

13.Use appropriate Conditional verb- form:

1. If I was offered the job, I think I (take) it.
2. If she (be) hungry, she would eat something.
3. If he studied, he (pass) the exam.
4. I (send) you a postcard, if I had your address.
5. What (happen), if you didn´t go to work tomorrow?
6. If she has enough money, she (buy) a new car.
7. What will John do, if he (not get) the job?
8. She would be terribly upset, if I (lose) her ring.
9. Many people would be out of work, if the factory (close) down.
10. What would you do, if you (be) the president of your country?

14. Read the information below. Discuss it in pairs and find additional information about implanting of video camera tubes, their variety.

Figure 18.3.Video camera tube

Video camera tubes in the early days of television used the photoelectric effect; newer variants used photoconductive rather than photoemissive materials.

Silicon image sensors, such as charge-coupled devices, widely used for photographic imaging, are based on a variant of the photoelectric effect, in which photons knock electrons out of the valence band of energy states in a semiconductor, but not out of the solid itself.

15.Say whether the following statements are true or false:

1. Sensors can be of double type.

2. Type of employed image sensor and the modifying effects are significant in machine vision characteristics.

3. Image smear can be reduced with the help of interline-transfer architecture.

4. The electron beam readout method accompanies with a number of disadvantages.

5. In newer variants of video camera tubes used neither photoconductive no photoemissive materials.

Open the brackets.

1. Paul (send) to prison. (Future tense)
2. My brother (just beat) in the race. (Present perfect)
3. He (tell) to wait outside. (Past tense)
4. I (not pay) for the work. (Past tense)
5. Policemen (often ask) for the way. (Present tense)
6. They lawn (cut) once a week. (Present tense)

7. We (ask) by the police. (Future tense)
8. The towels (not use). (Past tense)
9. He (not sell) the jewels. (Present perfect)
10. They (teach) French. (Present tense)
11. The fire brigade (phone) soon after the fire broke out. (Past perfect)
12. You (laugh) at if you talk such nonsense. (Future tense)
13. All the fruits (eat up) by the guests. (Past tense)
14. The letter (answer) tomorrow. (Future tense)
15. Stamps (sell) here. (Present tense)

Date: 2016-04-22; view: 949

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