The ink screen electronic price tag that can be placed in the refrigerator, it turns out this is how it is achieved!
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Author: Electronic Development Learning
Source: Electronic Development Learning Public Account
The ink screen electronic price tag that can be placed in the refrigerator, it turns out this is how it is achieved!
I've disassembled an electronic price tag before: it's really good! The five-yuan ink screen electronic price tag on Xianyu is really a bargain for those who know how to DIY. After this article was published, thousands of people in the comment area discussed whether supermarkets should use this electronic price tag system. If you are interested, you can click on the blue font to see it.
This time, my friend sent me a low-temperature electronic price tag so that I could explore its secrets. The size of this electronic price tag is the same as the one I disassembled before, but the shell color is light blue, and there are two more snowflakes in the lower left corner.
I went to Hanshuo's official website and found that the model is Nebular-213F. Its operating temperature is -25℃ to 0℃. I am curious, can this work at 0℃ to 40℃?
The back side looks like this.
After opening the back cover, I found the difference at a glance. The normal temperature price tag I disassembled before used two button batteries, but this one does not use button batteries, but this kind of block battery. The most important point in the FBI WARNING is that it cannot be charged.
After taking off the battery, I saw that it was from EVE Energy, model EF702338.
Remove the glue and you can see clearly.
This battery can be found on the official website of EVE Energy. It is a lithium-ion battery, 3.6V. The capacity is not small, 1600mAh. The operating temperature is -60℃~+85℃. This parameter is between Niu A and Niu C.
The entire battery is covered with a metal coating and looks very sturdy.
Unfortunately, the battery has probably been completely dead because it has been stored for too long. I measured it and found that there was no voltage. Since it cannot be charged, I dare not try to activate it. I just listen to advice.
Lithium thionyl chloride battery, also known as Li/SOCl2 battery. This battery has the highest capacity density among all actual mass-produced batteries, but its disadvantage is that the discharge rate is low and it is not rechargeable. The secret of the low temperature of the entire price tag is actually this battery. But since it has been disassembled, I will show you all the others.
It took some effort to remove the circuit board, and I found that the front panel was glued, so the whole body could not be preserved when I removed it.
Comparing the low-temperature price tag circuit board disassembled this time with the normal-temperature price tag circuit board disassembled before, we found that there are many similarities, such as the CC2640 chip used in both. The biggest difference is that the low-temperature price tag has an additional DC-DC chip. The crystal oscillator is different, and it is estimated that the crystal oscillator on the low-temperature price tag has a wider temperature range.
The DC-DC on the low-temperature price tag is TI's TPS62736, an ultra-low-power step-down converter with programmable output voltage and 50mA-200mA output current.
After looking at the manual, I found that the efficiency of this DC-DC is about 94% when the output current is 0.4mA~100mA.
From the back of the circuit board, the difference is that the low-temperature price tag is made of a battery, which is connected to the lithium-ion battery mentioned earlier. The normal-temperature price tag has the contact of a button battery behind it. In addition, it is found that the low-temperature price tag does not have a reed switch, so if you want to update the content, you may have to use the wireless background or NFC.
This kind of low-temperature price tag should be placed on the counters of supermarkets that need to keep fresh goods. After I published that article, a lot of people in the comment area discussed how expensive this kind of electronic price tag is and who would use it. But the fact is that many supermarkets are using it. For example, I went to Hema Fresh and found that all the goods in the supermarket were using this kind of electronic price tag. Pang Donglai seems to use this kind of ink screen electronic price tag as well.
The advantage of using this system for large supermarkets and chain supermarkets is that they can easily modify product prices in the background and update them quickly, which makes it easier for supermarkets to frequently change prices and promote sales. However, this system includes hardware + software + deployment + post-maintenance, and the cost is actually not low, so it is definitely not worth it for small-scale supermarkets and canteens to use this system.
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