使用ajax提交数据时获取null值

这是我的ajax代码。我不知道问题出在哪里，为什么它一直给我空值。

$('#btnSubmit').click(function(event) {
    var formData = {
        'name'              : $('input[name=name1]').val(),
        'branch_address'    : $('input[name=bAddress1]').val(),
        'officer_in_charge' : $('input[name=officer1]').val(),
        'contact_number'    : $('input[name=contactN1]').val()
    };
    $.ajax({
         type        : 'POST',
         dataType    : 'json',
         url         : "process_save.php",
         data        : formData,
         encode      : true
        })
}

输入值来自这里

<form id="form1">
    <div class="modal-body">
        <input type="text" class="form-control" name="name1" />
        <input type="text" class="form-control" name="bAddress1" />
        <input type="text" class="form-control" name="officer1" />
        <input type="text" class="form-control" name="contactN1" />
    </div>
    <div class="modal-footer">
        <input id="btnSubmit" type="submit" value="SUBMIT" class="btn" />
    </div>
</form>

process_save.php包含以下代码

if( !empty( $_POST ) ){
        // convert form data to json format
        $data = array(
          "name" => $_POST['name1'],
          "branch_address" => $_POST['bAddress1'],
          "officer_in_charge" => $_POST['officer1'],
          "contact_number" => $_POST['contactN1']
        ); //processes the fields on the form
        $json = json_encode( $data );
        $file = 'entries.json';
        // write to file
        file_put_contents( $file, $json, FILE_APPEND);
}