How use where for time format in MongoDB

Hi
I know my question not is about Codeigniter
But here is only i have my friends

So go to problem

I have many records that contain document {"id":"123123","date":"2019/2/2","time":"125123213"}
time value is timestamp

I can use range condition for date example between 2019/1/1 and 2019/1/20
But i cannot use range condition for time example 20:30 and 21:30

Do you help me?

Note:
my code where date condition is

PHP Code:

$searchCriteria =array('date' => array('$gte' => $date, '$lte' => $to_date));
$this->mongo_db->where($searchCriteria); 


Thanks