Safety mechanism for preventing accidental deployment of a utility knife blade

Abstract

A safety mechanism for a utility knife, including a razor blade mounted in a blade holder slideably mounted in a blade chamber in the housing. A first blade holder includes an arm extending therefrom with an engaging surface thereon. A second blade holder includes a tab extending therefrom. When either blade holder is deployed from the housing, the tab contacts the engaging surface, thereby preventing deployment of the other blade until the original blade is retracted.

1 ) A safety mechanism for a utility knife comprising: 
 an elongated housing having an apertured anterior end and an apertured posterior end;    an anterior blade chamber formed within the anterior end of the housing and aligned with the anterior aperture;    a posterior blade chamber formed within the posterior end of the housing and aligned with the posterior aperture;    an anterior blade holder slideably mounted in the housing and having an anterior blade-engaging portion positioned in the anterior blade chamber, and an arm operationally coupled to the anterior blade-engaging portion and extending substantially toward the posterior blade chamber, the arm having a contacting surface;    a posterior blade holder slideably mounted in the housing and having a posterior blade-engaging portion positioned in the posterior blade chamber, an extension operationally coupled to the posterior blade-engaging portion, and a tab coupled to the extension and adapted to selectively engage the contacting surface;    an anterior blade mounted in the anterior blade holder;    a posterior blade mounted in the posterior blade holder;    wherein the posterior blade holder is adapted to move between a recessed position wherein the posterior blade is completely within the housing and a deployed position wherein the posterior blade extends partially outside of the housing;    wherein the anterior blade holder is adapted to move between a recessed position wherein the anterior blade is completely within the housing and a deployed position wherein the anterior blade extends partially outside of the housing;    wherein the tab engages the contacting surface when one of the respective anterior and posterior blade holders are in the respective deployed position;    whereby if the anterior blade holder is in the deployed position, then the posterior blade holder cannot be moved from the recessed position; and    whereby if the posterior blade holder is in the deployed position, then the anterior blade holder cannot be moved from the recessed position.    
   
   
       2 ) The safety mechanism of  claim 1  further comprising a channel between the anterior blade chamber and the posterior blade chamber, wherein the arm passes through the channel.  
   
   
       3 ) The safety mechanism of  claim 2  further comprising a wall separating the anterior blade chamber from the posterior blade chamber, whereby the channel is formed in the wall.  
   
   
       4 ) The safety mechanism of  claim 1  further comprising: 
 an anterior safety chamber formed within the housing and oriented substantially parallel to the anterior blade chamber;    a posterior safety chamber formed within the housing and oriented substantially parallel to the anterior blade chamber;    the anterior blade holder having an anterior safety chamber engaging portion adapted to engage the anterior safety chamber; and    the posterior blade holder having a posterior safety chamber engaging portion adapted to engage the posterior safety chamber;    wherein the anterior and posterior safety chambers are adapted to releasably engage the respective anterior and posterior safety engaging portion of the respective anterior and posterior blade holders when the respective anterior and posterior blade holders are in the recessed positions;    wherein the respective anterior and posterior safety chambers are further adapted to prevent motion towards the respective anterior and posterior ends of the respective anterior and posterior engaged safety engaging portions; and    wherein the respective anterior and posterior blade holders must be pushed into the housing and away from the respective anterior and posterior apertures to release the respective anterior and posterior safety engaging portions from the respective anterior and posterior safety chambers, enabling the respective anterior and posterior blade holders to move into the deployed positions.    
   
   
       5 ) The safety mechanism of  claim 4  wherein the respective anterior and posterior safety engaging portions are positively biased into the respective anterior and posterior safety chambers.  
   
   
       6 ) The safety mechanism of  claim 1  wherein the respective anterior and posterior apertured ends are slits.  
   
   
       7 ) A utility knife comprising: 
 a housing;    a first blade holder;    a second blade holder; and    a safety mechanism which operationally couples the first blade holder and the second blade holder;    wherein the first blade holder is adapted to move between a first recessed position and a first deployed position;    wherein the second blade holder is adapted to move between a second recessed position a second deployed position;    wherein if the first blade holder is in the first deployed position, then the second blade holder cannot be moved from the second recessed position; and    wherein if the second blade holder is in the second deployed position, then the first blade holder cannot be moved from the first recessed position.    
   
   
       8 ) The utility knife of  claim 7  wherein the safety mechanism comprises: 
 an arm coupled to the first blade holder, the arm having an engaging surface;    a tab coupled to the second blade holder and adapted to engage the engaging surface when one of the respective first and second blade holders are in the respective first and second deployed positions.    
   
   
       9 ) The utility knife of  claim 7  further comprising: 
 a first blade chamber formed within the housing;    a second blade chamber formed within the housing; and    a channel between the first blade chamber and the second blade chamber;    wherein the first blade holder is substantially located within the first blade chamber, the second blade holder is substantially located within the second blade chamber and the safety mechanism passes through the channel.    
   
   
       10 ) The utility knife of  claim 9  further comprising a wall which separates the first blade chamber from the second blade chamber whereby the channel is formed in the wall.  
   
   
       11 ) The utility knife of  claim 9  further comprising: 
 a first safety channel formed within the housing and in communication with the first blade chamber;    a second safety channel formed within the housing and in communication with the second blade chamber;    the first blade holder having a first tab that is biased to engage the first safety channel when the first blade holder is moved into the first recessed position; and    the second blade holder having a second tab that is biased to engage the second safety channel when the second blade holder is moved into the second recessed position;    wherein the first blade holder must be moved toward the first recessed position before the first blade holder can be moved into the first deployed position; and    wherein the second blade holder must be moved toward the second recessed position before the second blade holder can be moved into the second deployed position.    
   
   
       12 ) The utility knife of claim ii wherein the respective first and second tabs are positively biased into the respective first and second safety chambers.  
   
   
       13 ) A utility knife comprising: 
 a housing;    a first blade holder;    a second blade holder;    a first blade mounted in the first blade holder;    a second blade mounted in the second blade holder; and    a safety mechanism which selectively couples the first blade holder and the second blade holder;    wherein the first blade holder is adapted to move between a first recessed position wherein the first blade is completely within the housing and a first deployed position wherein the first blade extends partially outside of the housing;    wherein the second blade holder is adapted to move between a second recessed position wherein the second blade is completely within the housing and a second deployed position wherein the second blade extends partially outside of the housing;    wherein if the first blade holder is in the first deployed position, then the second blade holder cannot be moved from the second recessed position; and    wherein if the second blade holder is in the second deployed position, then the first blade holder cannot be moved from the first recessed position.    
   
   
       14 ) The utility knife of  claim 13 , wherein the safety mechanism comprises: 
 an arm operationally coupled to the first blade holder, the arm having a contacting surface; and    an extension operationally coupled to the second blade holder and adapted to selectively engage the contacting surface when one of the respective first and second blade holders are in the respective first and second deployed positions.    
   
   
       15 ) The utility knife of  claim 13 , further comprising: 
 a first blade chamber formed within the housing;    a second blade chamber formed within the housing; and    a channel between the first blade chamber and the second blade chamber;    wherein the first blade holder is substantially located within the first blade chamber, the second blade holder is substantially located within the second blade chamber and the safety mechanism passes through the channel.    
   
   
       16 ) The utility knife of  claim 15 , further comprising a wall which separates the first blade chamber from the second blade chamber whereby the channel is formed in the wall.  
   
   
       17 ) The utility knife of  claim 15 , further comprising: 
 a first safety channel formed within the housing and in communication with the first blade chamber; and    the first blade holder having a first tab that is biased to engage the first safety channel when the first blade holder is moved into the first recessed position;    wherein the first blade holder must be moved toward the first recessed position before the first blade holder can be moved into the first deployed position.    
   
   
       18 ) The utility knife of  claim 17  wherein the first tab is positively biased into the first safety chamber.  
   
   
       19 ) The utility knife of  claim 15 , further comprising: 
 a second safety channel formed within the housing and in communication with the second blade chamber;    the second blade holder having a second tab that is biased to engage the second safety channel when the second blade holder is moved into the second recessed position;    wherein the second blade holder must be moved toward the second recessed position before the second blade holder can be moved into the second deployed position.    
   
   
       20 ) The utility knife of  claim 19  wherein the second tab is positively biased into the second safety chamber.