Abstract:
A device includes a trigger arrangement activating a function of the device. The trigger arrangement includes a trigger mechanism movable between a first position and a second position. The device also includes a feedback mechanism exerting a force biasing the trigger mechanism to the first position. The feedback mechanism produces a tactile feedback response when the trigger mechanism is moved from the first position.

Description:
FIELD OF INVENTION 
     The present application generally relates to trigger arrangements for electronic devices. 
     BACKGROUND INFORMATION 
     Electronic devices often include trigger arrangements that are used to access a functionality thereof. Trigger arrangements include mechanical triggers such as keypad buttons, push buttons and gun-style triggers. In certain applications, it is desirable to include a feedback response in order to indicate that the trigger has been successfully engaged. For example, pressing a key may produce a “click” that can be felt by a user. 
     In some situations, space, cost or other constraints may render the use of a conventional feedback mechanism difficult or impracticable. Consequently, the trigger arrangement may not be able to provide the user with adequate feedback. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a device which includes a trigger arrangement activating a function of the device. The trigger arrangement includes a trigger mechanism movable between a first position and a second position. The device also includes a feedback mechanism exerting a force biasing the trigger mechanism to the first position. The feedback mechanism produces a tactile feedback response when the trigger mechanism is moved from the first position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a trigger arrangement according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are provided with the same reference numerals. The present invention relates to trigger arrangements with a feedback response. Various embodiments of the present invention will be described with reference to a trigger arrangement for a handheld device (e.g., a bar code scanner). However, those skilled in the art will understand that the present invention may also be implemented in any other device that requires a trigger arrangement. Thus, the present invention may be implemented in, for example, mobile computers, radio-frequency identification (“RFID”) readers, cell phones, multimedia devices, automated teller machines, etc. 
       FIG. 1  shows an exemplary embodiment of a trigger arrangement  100  according to the present invention. The trigger arrangement  100  may be implemented in a handheld device such as a bar code scanner. For example, the trigger arrangement  100  may comprise a user-interfaceable portion of a detachable handle for the bar code scanner. The trigger arrangement  100  may include a gun-style trigger  110  that, when engaged by a user, enables a function of the handheld device. The trigger  110  may be formed of any substantially rigid material (e.g., plastic or metal) and may be shaped to conform to a curvature of a finger or multiple fingers. The trigger  110  may include an arm portion  112  with a pivoting proximal end  50 . The arm  112  may be formed integrally with the trigger  110  or, alternatively, coupled to the trigger  110  via any number of methods known in the art, such as welding, adhesives, mechanical interlocking, etc. 
     Rotation or movement of the trigger  110  may be defined by one or more movement limiting features disposed along a length thereof. For example, the trigger  110  may include a stopper  114  projecting from a proximal end of the trigger  110 . A length of the stopper  114  may vary depending on a size of the trigger  110 . In a neutral position, the stopper  114  may be separated from a stop guard  116 , which extends from a base of the trigger arrangement  100  and prevents further rotation of the trigger. As the trigger  110  is rotated through a range of movement, the stopper  114  eventually encounters the stop guard  116  and the trigger  110  is prevented from further rotation and/or movement. Thus, the distance between the stopper  114  and the stop guard  116  may define the range of trigger movement. The stopper  114  and the stop guard  116  may be formed of any substantially rigid material, but may not necessarily be of the same material. Those skilled in the art will understand that the stopper/stop guard arrangement described above is purely exemplary and other mechanisms for limiting trigger movement may be implemented in other embodiments. 
     The trigger arrangement  100  may further include a switching bracket  210  that includes an angled portion  212  terminating in a switching head  22 . The switching bracket  210  may rotate about a hinge  60  that enables the switching bracket  210  to rotate between a locked position  33  and a triggering position  35 . The switching bracket  210  may be mechanically coupled to the trigger arm  112  such that rotation of the trigger  110  causes the switching bracket  210  to rotate between the locked and triggering positions  33 ,  35 . For example, the distal end  50  may push against the switching bracket  210  with a force sufficient to bring the switching bracket  210  into the triggering position  35 . 
     The switching head  22  may include a magnet  20  that activates a switch  90 . In one exemplary embodiment, the switch  90  may be a reed switch that is activated when the magnet  20  is brought into proximity to the switch  90  (e.g., when the switching bracket  210  is in the triggering position  35 ). If the switch  90  is a normally open switch, a magnetic field exerted by the magnet  20  upon the switch  90  may cause switching components within the switch  90  to come into contact with each other, placing the switch  90  into a closed position. Alternatively, if the switch  90  is a normally closed switch, the magnet  20  may cause the switching components to separate, placing the switch  90  into an open position. 
     The switching head  22  may also include a stop ridge  24  extending from an end thereof. The stop ridge  24  may define the triggering position  35  by contacting a sidewall  26  that extends from the base of the trigger arrangement  100 . When the stop ridge  24  contacts the sidewall  26 , the switching head  22  may no longer be able to move further away from the locked position  33  and comes to a stop at the triggering position  35 . 
     The switching bracket  210  may be returned to the locked configuration  33  from the triggering position  35  by a spring (e.g., a coil spring) disposed within the hinge  60 . The coil spring may be biased towards the locked position  33 , resisting movement of the switching bracket  210  towards the triggering position  35 . The coil spring may provide a constant rate of triggering resistance (e.g., as a function of a spring constant and a displacement of the spring) that can be tactilely sensed by the user as a perceived resistance against a triggering motion (e.g., trigger rotation). The perceived resistance may be felt as a steadily increasing force that reaches a maximum when the triggering position  35  is reached. Because the resistance is steady and continuous, the coil spring may not provide any feedback to confirm that the trigger arrangement  100  has been successfully activated. As will be described in detail below, the exemplary embodiments of the present invention provide a feedback mechanism by which the user may be provided with feedback that indicates the trigger  110  has been activated. This feedback may comprise a sudden change in a force with which the trigger arrangement  100  resists the triggering motion. This change may translate to a “clicking” sensation that can be felt by the user via the trigger  110 . 
     Those skilled in the art will understand that any type of switch may be utilized as the switch  90 . For example, in another embodiment, the switch  90  may be a contact switch activated by physical contact with the switching head  22 . In yet another embodiment, the switch  90  may be a vibration sensitive switch that reacts to vibrations caused when the switching bracket  210  enters the triggering position  35  from the locked position  33 . Thus, in some embodiments, the magnet  20  may not perform any switching functions. However, as will be described below, the magnet  20  may, nevertheless, perform a feedback function. This may be true regardless of whether the magnet  20  induces opening and/or closing of the switch  90 . 
     The switch  90  may be mounted on a circuit board  15  or substrate of the handheld device. Activation (e.g., opening or closing) of the switch  90  may enable a functionality of the handheld device (e.g., enabling a bar code scanning arrangement). The circuit board  15  may comprise any number of electronic components such as a microcontroller or processor, a memory, signal processing components, etc. The switch  90  may be directly coupled to one or more of the circuit board components. Alternatively, output from the switch  90  may be indirectly coupled to the circuit board components, along with output from additional switches and/or other input signals, via a signal bus or an intermediate component such as a buffer. 
     In addition to providing a mechanism by which the switch  90  may be activated, the trigger arrangement  100  may enable a feedback response in the form of a tactile “click” that can be felt by the user when the switching bracket  210  moves from the locked position  33  to the triggering position  35 . As discussed above, the feedback response may be a function of the magnet  20 , which acts upon an iron object (e.g., an iron stud  80 ) located proximal to the magnet  90  when the switching bracket  210  is in the locked position  33 . The magnet  20  attracts the iron stud  80 , which is secured to the base of the triggering arrangement  100 , proximal of the switching head  22 . Because the iron stud  80  may be situated away from the triggering position  35 , a force of magnetic attraction between the magnet  20  and the iron stud  80  resists triggering. The user must exert enough force against the trigger  110  to disengage the switching bracket  210  from the locked position  33 . Once the exerted force is sufficient to causing disengaging, the switching bracket  210  is suddenly released from magnetic holding, which results in a clicking sensation that comprises the feedback response. Neither the magnet  20  nor the switching head  22  need be in actual contact with the iron stud  80  in order to achieve the feedback response. That is, it may be sufficient that the magnet  20  act upon the iron stud  80  at a distance. 
     The magnetic force between the magnet  20  and the iron stud  80  may determine a snap ratio for the trigger arrangement  100 . The snap ratio may be defined as an equation (F 1 −F 2 )/F 1 , where F 1  is an actuation force and F 2  is a contact force. The actuation force F 1  represents an amount of force that must be exerted by the user on the trigger  110  in order to bring the switching bracket  210  from the locked position  33  to the triggering position  35 . This may be a function of the magnetic force and/or a force exerted by the trigger arm  112  on the switching bracket  210 . The contact force F 2  represents an amount of force required to maintain the switching bracket  210  in the triggering position  35 . That is, the user must exert a minimum force (F 2 ) in order to maintain the stop ridge  24  in contact against the sidewall  26 . Otherwise, the coil spring in the hinge  60  may return the switching arm  210  to the locked position  33 . A high snap ratio (e.g., a small F 2  relative to F 1 ) may indicate a more forceful feedback response. 
     The snap ratio may be adjusted to achieve a desired level of feedback by varying any number of parameters of the triggering arrangement  100 . For example, if a higher actuation force F 1  is desired, a stronger magnet  20  may be used. A material from which the stud  80  is made may also be changed depending on the desired feedback level. For example, a higher actuation force F 1  may correspond to use of a ferromagnetic material or ferromagnetic alloy (e.g., iron, nickel, cobalt, etc.), which exhibits a strong attraction to magnetic forces exerted thereupon by the magnet  20 . If a lower actuation force F 1  is desired, a paramagnetic material (e.g., aluminum) and/or a weaker magnet  90  may be used. Other feedback parameters may include, for example, a distance between the magnet  20  and the stud  80 , a geometry of the magnet  20  and/or the stud  80 , a strength of the coil spring, etc. 
     The exemplary embodiments of the present invention enable a feedback response in situations in which achieving feedback using conventional trigger arrangements would be difficult or impossible. The trigger arrangement  100  has minimal space and hardware requirements. Furthermore, the teachings of the present invention may be implemented in conventional trigger arrangements without interfering with existing functionalities of the conventional arrangements, such as existing trigger mechanisms. The exemplary embodiments of the present invention may be implemented in applications where there is limited space to implement conventional feedback mechanisms, or where it is too expensive to do so. 
     In addition, the trigger arrangement  100  is able to confirm that it has been activated successfully. This may be useful in situations where the user cannot visually or audibly confirm trigger activation. The user may also derive a psychological benefit from feeling the clicking of the trigger arrangement  100 , since clicking is often associated with a high quality product (e.g., in terms of reliability, build quality, durability, etc.). 
     The exemplary embodiments of the present invention also allow the ability to adjust a level of feedback. By varying trigger parameters, a high snap ratio may be achieved in applications where more feedback is desired. If less feedback is required, the trigger arrangement  100  may be designed with a lower snap ratio. Thus, different trigger arrangements may be utilized depending on a particular application. 
     The present invention has been described with reference to the above exemplary embodiments. One skilled in the art would understand that the present invention may also be successfully implemented if modified. Accordingly, various modifications and changes may be made to the embodiments without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings, accordingly, should be regarded in an illustrative rather than restrictive sense.