Problem with PlayerHealth and renderer

I have built a playerHealth script and I did when the player loses life, meshrenderer to blink every 1 second but when he receives damage do more than once because when he feels damage and boolean when is activated, I have made is activated and make multiple times instead of a. How can I do to flash as I want? See the code:

 var curHealth : int = 70;
 var maxHealth : int = 100;
 var deadMode = false;
  
 var curProtect = false;
 static var damageCost = 10;
  
 function Update () {
     if(curHealth >= maxHealth) {
        curHealth = maxHealth;
     }
  
     if(curHealth <= 0) {
        curHealth = 0;
        deadMode = true;
     }
  
     if(curHealth > 0) {
        deadMode = false;
     } 
  
     protectedMode();
 }
  
 function OnTriggerEnter( other : Collider) {
     if(other.tag == "Enemy" && !curProtect) { 
        curProtect = true;
        curHealth -= damageCost;
     }
 }
  
 function protectedMode() {
  
     if(curProtect) {
          graphicsSkin = transform.Find("Graphics");
  
  
          graphicsSkin.renderer.enabled = false;
          yield WaitForSeconds(1);
  
          graphicsSkin.renderer.enabled = true;
          yield WaitForSeconds(1);
          graphicsSkin.renderer.enabled = false;
          yield WaitForSeconds(1);
  
          graphicsSkin.renderer.enabled = true;
          yield WaitForSeconds(1);
          graphicsSkin.renderer.enabled = false;
          yield WaitForSeconds(1);
  
          graphicsSkin.renderer.enabled = true;
          yield WaitForSeconds(1);
  
        curProtect = false;
     }

}