D100 Smart Lock Door Ajar Warning

The Homesmart.sg Aqara D100 Smart Door Lock is an electronically-operated, fully automated door lock. This means that it can achieve certain functions automatically, such as bolting your doors locked when your door is closed.

As with any electronic device, these automations are easy to use and seems to be relatively easy to implement, but when you break it down, there are several steps for every process. Let’s take automatic locking as an example:

1. Ensure door is in an OPEN position
2. Sense that door is going from a OPEN state to a CLOSE state
3. Ensure door is fully closed
4. Trigger motors to bolt the door

Without any of these steps, errors and problems could occur within the locking process. For example, if the door isn’t fully closed, the motors moving the bolts may damage the door frame or the lock itself when it smashes into a solid surface, instead of into the void in the door frame.

Thus, when these processes are created, attention has to be given to each of these steps. Since we’re talking about a “Door Ajar” warning, this is actually really relevant to step 3 – ensuring the door is fully closed.

How the lock knows the door is closed

In the Homesmart.sg Aqara D100, there are 3 main door latches and bolts-

  1. The scissor latch, which works as your normal door latch
  2. The set of 3 bolts, which works as your main lock
  3. The door sensor, which is a freely moving latch on a spring

In a normal operation, closing the door would mean this:

  1. Scissor latch gets pushed in by the strike plate, then finally extends fully into the void in the door frame (to secure the door)
  2. The door sensor latch gets pushed in by the strike plate, and remains pushed in
  3. Bolts extend into the door frame to lock the door

This means that for the lock to know when the door is closed, two variables must be satisfied:

1. The scissor latch must be fully extended
2. The door sensor must be pushed in

Door Ajar

This also means that if any of these variables isn’t in place, it means the door is either OPEN or AJAR.

To know if a door is open, it’s simple – by checking to see if the door sensor latch is fully extended. If it is, the door is open.

If either the scissor latch or the door sensor is pushed in, that means the door is ajar.

The Homesmart.sg Aqara D100 smart door lock will then sound an alarm that the door is ajar, and that the user should close it!

Why do we need an alarm?

It’s simple! One word – security.

When your door is ajar, the smart door lock does not bolt in. Bolting in when the door is ajar presents a risk of damaging your door, lock, or frame. At the same time, not bolting in means your door isn’t locked.

It thus makes sense for your lock to remind you to let it do its job – close the door fully so it can lock itself!

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