jQuery(document).ready(function($){
    $('#<?php echo $this->get_field_id( 'bg_color_1' ); ?>').wpColorPicker();
});

$('#<?php echo $this->get_field_id( 'bg_color_1' ); ?>').wpColorPicker({
    change: function(event, ui) {
        $('#<?php echo $this->get_field_id( 'bg_color_1' ); ?>').change();
    }
});