将Zend_Form_Element_Text转换为Zend_Form_Element_Hidden

In my controller script I have the following:

$customer_el = $this->view->form->getElement('customer_id');
Zend_Debug::dump($customer_el);

The output of it is

object(Zend_Form_Element_Text)#13 (26) {
  ["helper"] => string(8) "formText"
  ["_allowEmpty":protected] => bool(true)
  ["_autoInsertNotEmptyValidator":protected] => bool(true)
  ["_belongsTo":pro
... and so on.....

Is it possible to convert the $customer_el variable to Zend_Form_Element_Hidden ?? If so, how?