3.2 · Input and output devices
3.2 · 输入与输出设备
Getting data in and results out
数据的输入与结果的输出
What an input device and an output device are for, the devices you need to know by name, and the sensors that feed a monitoring or control system, including how to pick the right one for a situation.
输入设备与输出设备各自的用途、你需要记住名称的具体设备,以及为监测或控制系统提供数据的传感器,包括如何根据具体情况选择合适的传感器。
Explainer · 3.2.1
讲解 · 3.2.1
Input devices
输入设备
An input device lets a user or the surroundings put data into a computer. It converts a real-world action or measurement into a form the computer can process. It is needed because a computer cannot act on anything until data is given to it.
输入设备让用户或周围环境能把数据输入计算机。它把现实世界中的动作或测量结果转换成计算机能处理的形式。之所以需要它,是因为计算机在获得数据之前无法对任何事物采取行动。
| Input device | 输入设备 | Typical use | 典型用途 |
|---|---|---|---|
| Keyboard | 键盘 | entering text and numbers | 输入文本和数字 |
| Optical mouse | 光电鼠标 | pointing and selecting on screen | 在屏幕上指向和选择 |
| Microphone | 麦克风 | recording sound, voice commands, voice notes | 录制声音、语音命令、语音备忘 |
| Digital camera | 数码相机 | capturing photos and video | 拍摄照片和视频 |
| Barcode scanner | 条形码扫描器 | reading a product barcode at a checkout or in a warehouse | 在收银台或仓库中读取产品条形码 |
| QR code scanner | 二维码扫描器 | reading a QR code, often with a phone camera, to open a link or details | 读取二维码,常通过手机摄像头,以打开链接或详细信息 |
| Touch screen | 触摸屏 | direct on-screen input by touch (resistive, capacitive, infra-red) | 通过触摸直接在屏幕上输入(电阻式、电容式、红外式) |
| 2D / 3D scanner | 2D / 3D 扫描仪 | scanning a flat document (2D) or the shape of a physical object (3D) | 扫描平面文件(2D)或实体物品的形状(3D) |
Explainer · 3.2.2
讲解 · 3.2.2
Output devices
输出设备
An output device presents the results of processing in a form a person can use, or acts on the physical world. It is needed so that the work the computer has done is actually usable.
输出设备以人可以使用的形式呈现处理结果,或对物理世界产生作用。之所以需要它,是为了让计算机所做的工作真正能被利用。
| Output device | 输出设备 | Typical use | 典型用途 |
|---|---|---|---|
| LCD screen / LED screen | LCD 屏幕 / LED 屏幕 | displaying the interface; LED screens suit large, bright outdoor displays | 显示界面;LED 屏幕适合大型、明亮的户外显示 |
| DLP projector / LCD projector | DLP 投影仪 / LCD 投影仪 | projecting the display onto a large screen for a presentation | 将显示内容投影到大屏幕上以供演示 |
| Inkjet printer | 喷墨打印机 | a few pages, or a one-off photo, in good-quality colour | 少量几页,或一次性打印高质量彩色照片 |
| Laser printer | 激光打印机 | fast, high-volume printing, colour or black and white | 快速、大批量打印,彩色或黑白 |
| 3D printer | 3D 打印机 | building a solid object layer by layer from a design | 根据设计逐层构建实体物品 |
| Speaker | 扬声器 | producing sound from the computer | 发出计算机产生的声音 |
| Actuator | 执行器 | producing physical movement: turning a motor, opening a valve, moving a robot arm | 产生物理运动:转动马达、打开阀门、移动机械臂 |
An actuator is not used to “change what is on the screen”. It is a motor, valve or relay that makes something physically move. A screen is driven directly by the computer, not by an actuator.
执行器不是用来"改变屏幕上显示的内容"的。它是使某物发生物理运动的马达、阀门或继电器。屏幕是由计算机直接驱动的,而不是由执行器驱动的。
Try it yourself
动手试试
Input or output
是输入还是输出
Tag each device, then check. A sensor counts as an input device.
为每个设备打上标签,然后检查答案。传感器算作输入设备。
Explainer · 3.2.1
讲解 · 3.2.1
Touch screen types
触摸屏类型
The syllabus names three. You do not need the internal physics, but you should be able to pick the right one for a situation.
考纲列出了三种类型。你不需要了解其内部的物理原理,但应该能够根据具体情况选出正确的一种。
| Type | 类型 | Multi-touch | 多点触控 | Works with | 适用于 | Best for | 最适合 |
|---|---|---|---|---|---|---|---|
| Capacitive | 电容式 | yes (projective type) | 支持(投射式) | bare finger or special stylus, not ordinary gloves | 裸手指或专用触控笔,普通手套不行 | smartphones and tablets: sharp, bright, durable | 智能手机和平板电脑:清晰、明亮、耐用 |
| Resistive | 电阻式 | no | 不支持 | finger, any stylus, gloved hand | 手指、任何触控笔、戴手套的手 | rugged or industrial use; press harder, lower clarity | 坚固耐用或工业用途;需用力按压,清晰度较低 |
| Infra-red | 红外式 | yes | 支持 | finger, stylus, gloved hand; still works if scratched | 手指、触控笔、戴手套的手;即使被划伤仍能使用 | large screens and interactive whiteboards | 大屏幕和互动白板 |
Try it yourself
动手试试
Compare touch screens
比较触摸屏
Click a type to see where it fits and where it does not.
点击某种类型,查看它适合哪些场合、不适合哪些场合。
Explainer · 3.2.3
讲解 · 3.2.3
Sensors
传感器
A sensor is an input device that measures a physical quantity from its surroundings and sends the reading to the computer. Its purpose is to let a system respond automatically to conditions without a person watching.
传感器是一种输入设备,它测量周围环境中的某个物理量,并把读数发送给计算机。其目的是让系统能在无人值守的情况下自动对环境状况做出反应。
A sensor sends readings continuously, not only when something changes. It has no idea whether a value is “good” or “bad”. It is the microprocessor that compares each reading against stored values and decides whether to act.
传感器持续不断地发送读数,而不仅仅是在发生变化时才发送。它并不知道某个数值是"好"还是"坏"。是微处理器将每一次读数与存储的数值进行比较,并决定是否采取行动。
Most readings are analogue, so they pass through an analogue-to-digital converter (ADC) before the microprocessor can use them. To drive a motor or valve, a digital signal passes back through a digital-to-analogue converter (DAC) to an actuator.
大多数读数都是模拟信号,因此必须先经过模数转换器(ADC),微处理器才能使用它们。为了驱动马达或阀门,数字信号需要再经过数模转换器(DAC)转换后传给执行器。
| Sensor | 传感器 | Measures | 测量内容 | Example use | 示例用途 |
|---|---|---|---|---|---|
| Temperature | 温度 | how hot or cold the surroundings are | 周围环境的冷热程度 | a central heating system; a greenhouse | 中央供暖系统;温室 |
| Pressure | 压力 | force pressed on a surface | 施加在表面上的压力 | weighing a lorry at a weighbridge; an intruder standing on a mat | 地磅称量货车重量;有人踩在防盗垫上 |
| Light | 光线 | brightness of light | 光线的亮度 | switching street lights on at dusk | 在黄昏时自动开启路灯 |
| Infra-red | 红外线 | an infra-red beam being broken, or heat given off | 红外光束被遮挡,或物体散发的热量 | a burglar alarm beam across a doorway | 横跨门口的防盗报警光束 |
| Proximity | 接近 | whether an object is nearby | 是否有物体靠近 | turning off a phone screen when it is held to the ear | 手机贴近耳朵时自动关闭屏幕 |
| Acoustic | 声学 | sound | 声音 | detecting footsteps or breaking glass in a security system | 在安防系统中检测脚步声或玻璃破碎声 |
| Gas | 气体 | level of a gas such as oxygen or carbon dioxide | 氧气或二氧化碳等气体的含量 | monitoring air quality; CO₂ in a greenhouse | 监测空气质量;温室中的二氧化碳浓度 |
| pH | pH 值 | acidity or alkalinity | 酸碱度 | controlling acidity in a chemical process or soil | 控制化学过程或土壤中的酸度 |
| Moisture | 湿度(水分) | water content of a material such as soil | 土壤等材料的含水量 | keeping greenhouse soil from drying out | 防止温室土壤变干 |
| Humidity | 湿度(空气) | water vapour in the air | 空气中的水蒸气含量 | a chip factory; a greenhouse | 芯片工厂;温室 |
| Magnetic field | 磁场 | a changing magnetic field | 变化的磁场 | anti-lock braking; detecting a passing wheel | 防抱死制动;检测经过的车轮 |
| Accelerometer | 加速度计 | acceleration and a change in motion | 加速度及运动状态的变化 | rotating a phone display; triggering a car airbag | 旋转手机屏幕方向;触发汽车安全气囊 |
| Flow | 流量 | rate a liquid or gas is moving | 液体或气体流动的速率 | gas flow in a pipe; a hospital breathing machine | 管道中的气体流量;医院的呼吸机 |
| Level | 液位 | height of a liquid or solid in a container | 容器中液体或固体的高度 | fuel in a car tank; water height in a river | 汽车油箱中的燃油量;河流的水位 |
“A temperature sensor measures the temperature” is not an answer to a scenario question, apply it: “the temperature sensor checks the greenhouse air, and the microprocessor turns on the heater if it falls below the set value.” “Motion sensor” is not a valid name, use infra-red or accelerometer.
"温度传感器测量温度"这样的答案回答不了情境题,要把它应用到具体情境中:"温度传感器检测温室内的空气,如果温度低于设定值,微处理器就打开加热器。""运动传感器"不是一个合法的名称,应使用红外线传感器或加速度计。
Try it yourself
动手试试
Choose a sensor
选择传感器
For each situation, pick the most suitable sensor from the list.
针对每种情境,从列表中选出最合适的传感器。
Try it yourself
动手试试
Monitoring vs control
监测与控制
Both start the same way. Step through to see where they differ.
两者的开头是一样的。逐步演示,看看它们在哪里出现分歧。
Check your understanding
检验你的理解
What is an actuator used for?
执行器的用途是什么?
Check your understanding
检验你的理解
When does a sensor send data to the microprocessor?
传感器在什么时候向微处理器发送数据?
Check your understanding
检验你的理解
Which input device is most suitable for adding a spoken note to a smartphone?
哪种输入设备最适合在智能手机上添加一条口述备忘录?
Common mistakes
常见错误
3.2.1 to 3.2.3
考官针对 3.2.1 至 3.2.3 报告了以下模式
RecurringCandidates say an actuator changes the screen display. An actuator produces physical movement only: a motor, a valve, a robot arm.
反复出现考生说执行器会改变屏幕显示。执行器只产生物理运动:马达、阀门、机械臂。
On sensors: candidates think a sensor only sends data when something is detected. It sends a continuous stream; the microprocessor compares readings with stored values and decides what to do.
在传感器方面:考生认为传感器只有在检测到某种情况时才发送数据。实际上它发送的是持续的数据流;由微处理器将读数与存储的数值比较,并决定该怎么做。
Sensor answers are generic: “a temperature sensor measures temperature”, not applied to the scenario. And “motion sensor” or “movement sensor” is given, which is not a sensor on the list; the answer is infra-red or accelerometer.
关于传感器的答案往往过于笼统:"温度传感器测量温度",没有联系到具体情境。还有考生给出"运动传感器"或"移动传感器"这样的答案,而这不在传感器列表上;正确答案应是红外线传感器或加速度计。
For a given context, candidates name a device that does not fit: a mouse and keyboard for a smartphone, or a printer as the output for a device that has no printer. Match the device to both the task and the equipment in the scenario.
在给定情境中,考生说出了不合适的设备:给智能手机配鼠标和键盘,或把打印机当作没有打印机的设备的输出方式。要让设备既符合情境中的任务,也符合情境中的设备本身。
Generic: “A moisture sensor is used. It sends data to the microprocessor which is converted to binary.”
笼统:"使用湿度传感器。它把数据发送给微处理器,数据被转换成二进制。"
Applied: “A moisture sensor continuously reads the soil water level. An ADC converts each reading to digital. The microprocessor compares it with the stored minimum; if the soil is too dry it signals an actuator to open the water valve.”
联系情境:"湿度传感器持续读取土壤水分含量。ADC 把每次读数转换成数字信号。微处理器将其与存储的最小值比较;如果土壤太干,就向执行器发出信号,打开水阀。"
Wrong device for the context: “To output the result on the fitness tracker, use a printer.”
不符合情境的设备:"要在健身追踪器上输出结果,使用打印机。"
Fits the device: “The fitness tracker shows the result on its small LCD screen.”
符合设备:"健身追踪器在其小型 LCD 屏幕上显示结果。"
Revision questions
复习题
Past-paper style. Write an answer, then reveal the marking points and mark yourself.
采用历年真题风格。写下答案,然后展开评分要点给自己打分。
[2]State what is meant by an output device, and give one reason it is required.
[2]陈述输出设备的含义,并给出一个需要它的理由。
Marking points
评分要点
- An output device presents the results of processing in a form a person can use, or acts on the physical world.
- It is required so that the work the computer has done can actually be seen or acted on.
- 输出设备以人能使用的形式呈现处理结果,或对物理世界施加动作。
- 之所以需要它,是为了让计算机所做的工作能被看到或被据此行动。
[3]A drone must avoid hitting objects in front of it. Name a suitable sensor and describe how it works with the microprocessor.
[3]一架无人机必须避免撞上前方的物体。说出一个合适的传感器,并描述它如何与微处理器协同工作。
Marking points
评分要点
- A suitable sensor: an infra-red / ultrasonic / proximity sensor.
- It continuously measures the distance to the nearest object ahead.
- Each reading is sent (via an ADC) to the microprocessor, which compares it with a stored minimum safe distance.
- If an object is too close, the microprocessor signals the motors / actuators to slow, stop or change direction.
- 合适的传感器:红外线 / 超声波 / 接近传感器。
- 它持续测量到前方最近物体的距离。
- 每个读数(经 ADC)送到微处理器,微处理器把它与存储的最小安全距离比较。
- 如果物体太近,微处理器给电机 / 执行器发信号,减速、停止或改变方向。
[4]Describe two differences between how a monitoring system and a control system use sensor data.
[4]描述监测系统与控制系统在使用传感器数据方式上的两处不同。
Marking points
评分要点
- Monitoring: the sensor readings are only recorded or displayed, or an alert is given; the system takes no action to change the conditions.
- Control: the readings are compared with stored values and the microprocessor also signals actuators to change the physical conditions; there is a feedback loop.
- 监控:传感器读数只被记录或显示,或发出提醒;系统不采取任何行动去改变条件。
- 控制:读数与存储的值比较,而且微处理器还给执行器发信号去改变物理条件;存在一个反馈回路。
[3]A tablet is used outdoors with gloved hands. State which touch screen type is most suitable and justify your choice.
[3]一台平板电脑在户外戴手套使用。陈述哪种触摸屏类型最合适,并说明理由。
Marking points
评分要点
- Most suitable: a resistive touch screen.
- Justify: it responds to pressure from any object, including a gloved finger, so it still works with gloves outdoors.
- A capacitive screen would not respond to an ordinary gloved hand.
- 最合适:电阻式触摸屏。
- 理由:它对任何物体的压力都有反应,包括戴手套的手指,所以在户外戴手套时仍能用。
- 电容式触摸屏对普通戴手套的手没有反应。
[2]Explain why an actuator, not the screen, is the output when a computer controls a barrier.
[2]解释为什么在计算机控制一道栏杆时,输出的是执行器而不是屏幕。
Marking points
评分要点
- The screen is driven directly by the computer and only displays information.
- Raising or lowering a barrier needs physical movement, which only an actuator (a motor) can produce.
- So the actuator that moves the barrier is the output, not the screen.
- 屏幕由计算机直接驱动,只显示信息。
- 抬起或放下栏杆需要物理运动,而只有执行器(电机)能产生。
- 所以移动栏杆的执行器才是输出,不是屏幕。
Flashcards
记忆卡片
Active recall for this subtopic’s key terms.
针对本子主题关键术语的主动回忆练习。
Keep this subtopic’s practice with you
把这个子主题的练习保存下来
Free account: unlock every revision question and flashcard for 3.2, and every other IGCSE 0478 statement.
免费账户:解锁 3.2 以及所有其他 IGCSE 0478 考纲陈述的全部复习题和记忆卡片。