jQuery未生成我的JSON

我正在尝试从表单生成一个JSON文档。我想要的输出如下所示:

{
    "name": "joe-pc",
    "device_type": "server",
    "os": "windows",
    "info": [
        {
            "net_info": [
                {
                    "ip": "192.168.0.5",
                    "name": "eth0"
                },
                {
                    "ip": "192.168.0.28",
                    "name": "eth1"
                }
            ]
        },
        {
            "OS_info": [
                {
                    "name": "windows"
                },
                {
                    "build": "123.1.3"
                }
            ]
        },
        {
            "whatever_info": [
                {}
            ]
        }
    ]
}

我得到的是:

{"info":[{}]}

代码段:

$('#top_three_next').click(function (e) {
        var json_obj = new Object();
        json_obj.name = $('#name').val(); //manditory
        json_obj.device_type = $('#device_type').val(); //manditory
        json_obj.os = $('#os').val(); //not a manditory field
        // is this not available outside the function? 
        // even if I declare json_obj as a global var?
    });

完整代码:

http://jsfiddle.net/jdell64/Tu9bB/ (从js窗格的第93行开始)。