I'm making a custom note meta box for plugin, and I have a note box input and one 'add' button in the box with. I want the add button do the add note action only, instead of updating the post such as the publish button.

    else {
            print '<hr />';
        }
        print '<div id="ppn_add_post_note" style="margin: 10px 0 10px 0;">';
        print '<label for="ppn_post_note">' . __('Add note:', 'peters_post_notes') . '</label><br />';
        print '<textarea rows="3" cols="30" name="ppn_post_note" id="ppn_post_note" style="width: 99%">
'.get_post_meta($post->ID, 'ppn_post_note', true).'
</textarea><br /><br />';
        print '<label><input type="checkbox" name="ppn_private" /> ' . __('Private note', 'peters_post_notes') . "</label>\n";
        print '</div>
<div style="text-align: right">
<input type="submit" value="Save" id="save_note">value="Add" tabindex="5" accesskey="p">

</div>

';
    }

Functions.php

            jQuery(document).on('click', '#save_note', function(e) {
                e.preventDefault();
                var note =  $('#ppn_post_note').val();

                var post_id = $('input[name="post_ID"]').val();
                var data = {
                    'post_id': post_id,
                    'note_movie': note,
                    'action': 'rt_note_save',
                }
                jQuery.post(ajaxurl, data, function(resp){
                });
            });
        });
    </script>
    <?php
}
add_action('wp_ajax_nopriv_rt_movie_serial_save', 'rt_movie_serial_save');
add_action( 'wp_ajax_rt_movie_serial_save', 'rt_movie_serial_save' );
function rt_movie_serial_save(){
    if (isset($_POST['key'])) {
        $key = $_POST['key'];
        $bk_name = $_POST['bk_name'];
        update_post_meta( $_POST['post_id'], 'serial-'.$key, $bk_name );
    }
    die();
}


add_action('wp_ajax_nopriv_rt_note_save', 'rt_note_save');
add_action( 'wp_ajax_rt_note_save', 'rt_note_save' );
function rt_note_save(){
    if (isset($_POST['note_movie'])) {
        $key = $_POST['note_movie'];
        $bk_name = $_POST['note_movie'];
        update_post_meta( $_POST['post_id'], 'ppn_post_note', $bk_name );
    }
    die();
}