这是描述信息

NEWS CENTER

Check category

Human contact detection and sensing technology used in fan-type electrical appliances

Human contact detection and sensing technology used in fan-type electrical appliances

Information

1. Abstract

This solution is mainly used for fan-type electrical products. When the motor of a traditional fan is running at high speed, due to the lack of induction detection mechanism, when a human hand or other metal object is inserted into the fan cover, the motor continues to run, and its danger. The sensor detection scheme is very meaningful. When a human hand or other metal objects are inserted or contacted with the fan cover, the fan motor must immediately stop rotating to minimize the danger.

In order to solve this problem, a human contact detection and control scheme is proposed. The sensor is directly connected to the product shell or installed in a place where people can easily access it through a special capacitive touch chip. The touch sensor chip always detects the condition of the sensor. When a human hand touches or approaches the sensor, the touch sensor chip sends a signal to the main control MCU . After the main control MCU receives the signal, it immediately operates the motor controller to let the motor immediately Stop turning.

 

 xb

 

2. Detailed description of this technical solution

1) Through a dedicated capacitive touch chip, using its fixed time charge and discharge technology, the A / D quantized signal of the charge and discharge of the capacitor is obtained in a unit time to detect the change in the capacitance value. By judging the change in the capacitance of the sensor, it is judged whether there is human contact. The sensor here selects the metal cover of the fan (can be painted), and directly connects a detection pin of the touch sensor chip to the fan cover.

2) When a human hand touches or approaches the fan cover, the capacitive touch sensor chip sends a signal to the MCU , and the signal can be high, low, or other communication methods.

3) The MCU detects the signal from the capacitive touch sensing chip, performs logic processing, and then operates the motor controller to stop the motor immediately.

 

3.1 Technical problems to be solved by this solution

1)产品的灵敏度要高,不能是整个手掌都贴到风扇罩上,才触发感应器,必须是当一个手指接触到风扇罩,也能触发触控传感芯片。 

2)产品的环境适应性要强,不能误操作。产品必须能够自动适应环境的变化,包括温度、湿度的变化。

3.2本方案的关键技术点

1)感应器的选择

       由于风扇网罩是金属的,适合做触控传感芯片的感应器,而且是人们最容易接触的地方,所以本方案采用电风扇的金属罩当做感应器的,直接连接到触控传感芯片的检测引脚上。

 

2)信息的采集

   触控传感芯片实时对感应器进行采样,人手或金属物没有接触网罩时的采样值为C1(量化单位),接触时的采样值为C2。实际变化情况会如下图

所示。

 

 

xb

 

从上图可以看出,人手或金属物没有接触网罩时,采样值很稳定,在很小的范围内波动。当人手或金属物逐渐靠近网罩时,采样值逐渐上升。触控传感芯片通过判断C1C2的差值Δ来判断人手或金属物是否接触,Δ大于设定的阈值则认为人手或金属物接触到网罩,否则没有接触。触控传感芯片不是一检测到Δ大于设定的阈值就给MCU发信号,必须是连续几个采样,Δ都大于设定的阈值才通知MCU有人手或金属物已经接触到网罩,以防外界的瞬间干扰,造成误触发。

关于C1C2的差值Δ有一点需要注意的是:由于风扇网罩的直径一般在40CM左右,比较大,它上面的寄生电容比较大,当人手或金属物靠近或接触时,触控传感芯片检测引脚上的电容(采样值的大小和电容容值成正比关系)变化量会比较小,得到的Δ会比较小,所以触发阈值不宜设置的过大,以防出现灵敏度过低的情况。

3)信息的传送

触控传感芯片检测到人手或金属物接触时,将信息发送给主MCU。通信方式可以是IO口通信方式,IO口平时为高电平,当人手或金属物接触风扇罩的时候,为低电平;也可以是其它通信方式(I2CUART都可以),只要按照约定的协议通信即可。

4)信息的处理

    MCU按照跟触控传感芯片约定好的通信方式和协议实时跟触控传感芯片保持联系,一检测到触发信息(触控传感芯片发的人手或金属物接触风扇罩的信息),立即操作电机控制设备,让电机停止转动。

3.3本方案产生的有益效果

  1)成功防止人手或金属物插入到风扇罩里时导致的危险发生,起到安全保护的作用。

  2 ) High sensitivity. When a finger touches the fan cover with a dedicated capacitive touch sensor chip, the detection equipment can be triggered , which can meet the needs of different types of fan applications and enhance the commercial value of intelligent detection technology products.

 

Shenzhen simbond Technology Co., Ltd

Address: room 701 and 702, building 12, Shenzhen Software Park Phase II, Keji Zhonger Road, Nanshan District, Shenzhen

Fax:0755-86338595

Zip:518057

这是描述信息
这是描述信息
这是描述信息

COPYRIGHT(©)2017 Shenzhen simbond Technology Co., Ltd 粤ICP备14005068号   Powered by  www.300.cn