[introduction] the parts of an apparatus that ambient light sensor is intensity of light of surroundings of a kind of induction. Experience in order to optimize a vision from self-adjusting indication brightness, to intelligence energy-saving, ambient light sensor is mixed with its diversification type run a principle, satisfying different applied requirement. The article will introduce a few common ambient light sensor type and application, choose a guideline, introduce a few common problems and solution.

Article overview 

Ambient light sensor is the parts of an apparatus of intensity of light of surroundings of a kind of induction. Experience in order to optimize a vision from self-adjusting indication brightness, to intelligence energy-saving, ambient light sensor is mixed with its diversification type run a principle, satisfying different applied requirement. The article will introduce a few common ambient light sensor type and application, choose a guideline, introduce a few common problems and solution.

The application of ambient light sensor

Ambient light sensor is a kind can all round the induction the device of radial intensity, use at adjusting normally the indication brightness of equipment, in order to promote the use of the user the experience. Common applied setting includes the brightness on the indication screen such as smartphone, flat and notebook computer to adjust. In addition, in electronic reader and TV, ambient light sensor also can be used at adjusting screen colour temperature, bring more comfortable read or view an experience.

In addition, in a lot of electron equipment, ambient light sensor can be used at saving the sources of energy. It is OK self-correcting carries brightness on the back, radial circumstance reduces specific power consumption all round the basis, in order to prolong battery service life. Photograph in digital camera and mobile phone in resembling a head, ambient light sensor can affect time of exposure and setting of other watch for an opportunity, in order to get used to different radial condition, rise film the effect. Indoors in lighting system, ambient light sensor can detect the brightness of surroundings, control indoor illume thereby, realize automatic illume to adjust, improve beneficial result of the sources of energy.

Sensor of 4 kinds of common ambient light reachs applicable setting

The sort of ambient light sensor and type are quite diversiform, its run a principle also each are not identical, will introduce a few common ambient light sensor for you below.

1.  Photosensitive resistor (LDR)

Photosensitive resistor (Light-Dependent Resistor, abbreviation LDR) it is a kind of parts of an apparatus that is applied extensively in ambient light sensor, photosensitive resistor leaves resistance in low luminous environment normally bigger, and resistance leaves in tall luminous environment lesser, its change through measuring resistance, those who will feel the light is strong weak.

The brightness that sensor of photosensitive resistor ambient light is applied at equipment normally is self-adjusting function, through monitoring the change of ambient light line, equipment is OK the brightness of brightness of self-correcting indication screen or lighting equipment, offer what fit current light requirement more to show the effect or illume. Because can realize automatic brightness to adjust, sensor of photosensitive resistor ambient light conduces to economic energy resources. When the light is enough, can reduce the brightness of indication screen, reduce the specific power consumption of equipment, this is particularly important in mobile equipment.

Photosensitive resistor differs to what smooth susceptibility follows wavelengh and change. Normally, it is relatively sensitive to visible light area, but relatively inferior to the susceptibility of infrared ray and ultraviolet ray. Photosensitive resistor has proper time to answer to smooth change, but the parts of an apparatus that it is not real time reaction, however the elapse as time, can get used to new luminous environment gradually.

The resistance of photosensitive resistor still suffers temperature effect, because this is in application,need considers temperature to be opposite the influence of its function. Photosensitive resistor is a kind of relatively cheap photosensitive sensor, and be used very easily. Its production cost is low, apply to all sorts of application setting.

2.2. Photoelectricity diode (Photodiode)

Photoelectricity diode (Photodiode) it is a kind of semiconductor device that uses Yu Guang response, it is applied extensively in smooth sensor, include ambient light sensor. Photoelectricity diode can change smooth signal to be voltaic signal, its output electric current and radial intensity to become direct ratio, the ambient light sensor of this kind of type can be used at measuring smooth intensity accurately.

Photoelectricity diode has taller sensitivity normally, can detect inside wide spectral range the light, this makes it can offer accurate light to pass feeling property below different luminous environment. When photoelectricity diode has fast noise to answer, can react the light changes quickly, this makes it is in the application that needs real time sex very effective, for example camera exposure is controlled or automatic brightness adjusts.

Below low luminous environment, the dark current of photoelectricity diode (the electricity that produces below the illuminate that do not have light) relatively inferior, this conduces to raise letter a confusion of voices to compare. The output of photoelectricity diode has linear concern of height between electric current and radial intensity, this means the size that can export electricity through measuring photoelectricity diode, will estimate the strength of ambient light well and truly.

The spectrum of photoelectricity diode is answered depend on normally its material and production means, diode of a few photoelectricity is sensitive to visible light area, and a few otherer the likelihood has taller susceptibility to infrared ray or ultraviolet ray. Work to make photoelectricity diode correct, it needs the means work with retrorse bias voltage normally, this kind of bias voltage ensures photoelectricity diode also can generate dark current when be shot without illumination.

The effect that the function of photoelectricity diode suffers temperature to change is lesser, this makes it can be stabilized in different environment run. Photoelectricity diode makes small-sized parts of an apparatus or appliance normally, this makes it applies to a lot of need embedded in the application that sends feeling function solely. In addition, photoelectricity diode has relatively inferior power comsumption normally, this makes it more energy-saving in the application of batteries power supply.

3.3. Photoelectricity dynatron

Photoelectricity dynatron (Phototransistor) be felt to apply by wide application Yu Guangchuan, but this basically is the one part in serving as smooth sensor, the ambient light sensor with independent and rather than. Photoelectricity dynatron is parts of an apparatus of a kind of photosensitive, be similar to common electronic dynatron, but its basic function is electricity produces below smooth illuminate.

Photoelectricity dynatron basically uses the radial strength in Yu Chuangan surroundings, when radial illuminate arrives on photoelectricity dynatron, the intensity of the electric current of generation and light becomes direct ratio. Because photoelectricity dynatron has the character of enlarge, the smooth signal that it can input in the enlarge on certain level, heighten detected sensitivity. When photoelectricity dynatron has relatively fast noise to answer normally, this makes it is in the application that needs real time sex the result is favorable, below the radial condition that is used at rapid change for example.

The spectrum of photoelectricity dynatron is answered depend on its material and structure, different photoelectricity dynatron has different susceptibility to the light of different wavelengh. The enlarge multiple of photoelectricity dynatron interior affects his to convey feeling ability, some photoelectricity dynatron has higher enlarge multiple, this can be used at rising to believe comparing of a confusion of voices.

The function of photoelectricity dynatron suffers temperature effect, because this is in application,need considers temperature to convey sensibility to its can influence. Photoelectricity dynatron can make different measurement and appearance, make it can get used to all sorts of application setting, the mobile facility that includes miniaturization or compositive in other parts of an apparatus.

4.4.Sensor of IC ambient light

Sensor of IC ambient light (Integrated Circuit Ambient Light Sensor) be a kind compositive the integrated circuit that travels feeling function solely, use at measuring the illumination condition of surroundings normally. Sensor of these IC ambient light is had a series of function and character, make its apply to a variety of application setting.

Sensor of IC ambient light applies in the facility that needs self-adjusting brightness normally, it can summon the strength of feeling ambient light, show the brilliance of screen according to illumination circumstance self-correcting, provide better visual experience. Pass self-adjusting brightness, sensor of IC ambient light can reduce the power comsumption of equipment, prolong battery life, this is in mobile equipment and portable apparatus especially important.

Sensor of IC ambient light can summon the strength of sensitive line, offer numerical value or digital output, in order to show the luminance level of current luminous environment. Sensor of IC ambient light has taller response to the spectrum of visible light area normally, but its answer character to change possibly also somewhat inside different wavelengh limits. Sensor of a few IC ambient light supports a variety of operation pattern, for example adaptability brightness control, be in a poor light control, or of specific application setting optimize mode.

Sensor of IC ambient light normally very cabinet, suit to embed in all sorts of equipment, and easily compositive in the design. These sensor have character of low power comsumption normally, make its suit to apply in the mobile equipment that counts batteries power supply.

Sensor of most IC ambient light offers digital output, this makes they can direct as compositive as small controller or other figure system, go to the lavatory to seize processing and control into linage. These sensor can hold relatively stable property below different temperature normally, increased the stability that its apply. Because be the design of unifinication, sensor of IC ambient light normally easily compositive in all sorts of electron equipment, need not complex exterior circuit.

The key of choice of ambient light sensor and design thinks element

When choice and sensor of design ambient light, need considers many factors in order to ensure function and dependability.

• Use requirement clearly: For example automatic brightness adjusts, energy conservation, environment is monitored etc, this will conduce to the type of ambient light sensor that the choice suits and performance demand. The engineer can consider to use diode of photosensitive resistor, photoelectricity, still be sensor of IC ambient light, different sensor has different character, for example sensitivity, answer stability of time, temperature to wait.

• Spectral effect thinks: Need the spectral range of the consideration in specific applying especially, ensure the sensor of a choice can answer specific illuminant correctly.

• Temperature stability: The temperature of consideration application environment changes, a few sensor may be relatively sensitive to temperature change, and certain likelihood has better temperature to compensate function.

• Dynamic limits: Still need to ensure the ambient light sensor of a choice has enough dynamic range when the design, can answer the change below different luminous environment, this accurate to be being offerred below condition of different luminous intensity measurement the result is very important.

• Durable sex and stability: Be aimed at moving for long or the application below special environment, certain application setting may need more durable material or crust.

• Power comsumption: To portable the equipment with batteries power supply, should notice the power comsumption of sensor. Choose the ambient light sensor of low power comsumption, can improve battery life.

• Corrective with precision: If need the light of high accuracy to pass,feel, need to consider the corrective demand of sensor, a few sensor may need periodic corrective in order to ensure accuracy.

• Enclose with installation: Need those who consider sensor to enclose form and how to install in applying, sensor of a few ambient light may need additional protection or install specific direction and position, the sensor that the supplier offers differs on comparable market, evaluate its function and cost, the supplier with credible alternative is supplied for a long time with ensuring and the technology supports.

The common issue that ambient light sensor uses and solution

In applying an environment, ambient light sensor may face a few common problems, these problems may affect its function and accuracy.

A few smooth sensor may have penetrability difference to the material of specific type, bring about sensitive strength cannot be summonned correctly in specific environment, because this needs to choose to apply to the sensor with the better penetrability of specific application, perhaps adjust the position of sensor and direction, in order to ensure the light can arrive at sensor surface correctly.

The influence that the function of ambient light sensor may be changed by temperature, bring about inaccurate light to conduct move result. Should use the sensor that has good temperature to compensate function right now, perhaps add temperature to compensate circuit in the system, with corrective the error that causes by temperature change.

Ambient light sensor may be right the change of different illuminant (for example lamp of fluorescent lamp, LED) reaction is different, cause accuracy difference. Because this should use a variety of pair of illuminant to have good answered sensor, perhaps undertake in application corrective the illuminant that differs in order to suit.

If the dynamic limits of ambient light sensor is insufficient, the luminous environment that will not answer an extreme changes. Should choose to have the sensor of bigger dynamic range right now, perhaps add automatic gain control in the system (AGC) circuit, in order to enlarge the applied limits of sensor.

Should encounter unusual illuminant (for example sunshine twinkles point-blankly, by force solely) when, the likelihood brings about sensor to adjust brightness erroneously. Should use filter right now or shading equipment is added around sensor, in order to reduce the unusual illuminant effect to sensor. In addition, after be used for long, sensor function may drop, bring about accuracy to drop. Should be checked regularly accordingly and change the sensor of ageing, in order to ensure the long-term stability of ambient light sensor moves.

The noise in the environment outputs generation possibly also to sensor bad influence. Should use low noise sensor right now, perhaps use technology of digital filter wave on sensor output, in order to reduce the effect of noise. Electromagnetism interference may come from other electron equipment, generate interference to function of ambient light sensor. Because this considers interference rejection sex in the design, perhaps be all round sensor applied screen measure, in order to reduce electromagnetism interference.

Use afore-mentioned solution integratedly, the stability that can increase ambient light sensor to fall in different application setting and accuracy. Choose to answer with the design as specific application demand differ somewhat, because this is in application,should undertake adjustment according to particular case.

Summary

Ambient light sensor applies extensively already in all sorts of information communication products now. They not only can intelligent adjustment shows screen brilliance, optimize the visual experience of the user, still pass accurate control power comsumption, extend the use time of equipment significantly. In photography and illume domain, ambient light sensor is passed diagnose and acclimatization illuminant changes, promoted the show of equipment significantly, market application is quite wide. The ambient light sensor of article intermediary carry on is relevant information, believe conduce you are designed with sensor of choice ambient light. If have any idea, welcome and our communication discuss.

Article origin: DigiKey gets victory

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