A self-contained handle assembly for a door provides a light emitting diode which indicates whether the door is locked or unlocked. The LED blinks when the door is locked and thus provides an active reminder of the position of the deadbolt.

CROSS-REFERENCE TO RELATED APPLICATIONS 
   Priority is hereby claimed to provisional application Ser. No. 61/020,451, Filed Jan. 11, 2008, which is incorporated herein by reference. 


   FIELD OF THE INVENTION 
   This invention relates to a deadbolt latch handle or latch handle cover for use in door lock assemblies. More specifically, this invention relates to an illuminated signal (preferably a light-emitting diode) incorporated in the deadbolt latch handle or handle cover. The signal is activated when the latch handle is secured in a locked position, indicating that the deadbolt is engaged and the door is locked. 
   DESCRIPTION OF THE PRIOR ART 
   The ever increasing number of residential burglaries in recent years has intensified the need for alarm systems and effective locking mechanisms. Typical residential alarm systems include a plurality of sensor mechanisms at various entrance points, the sensors connected by external wiring to an indicator panel or some other control panel. Typical alarm systems often include a communication link for alerting law enforcement authorities to a break-in. Unfortunately, while such alarm systems provide a number of desirable features, they are quite expensive. In the case of an alarm system retrofit to an existing building, extensive external wiring and modification to the dwelling is usually required. Until complicated alarm systems become more affordable, the most effective deterrent to burglaries is a simply securely locked door. 
   Today, as many as 85-90 percent of all residential burglaries are perpetrated by non-professional burglars who take advantage of an unlocked entryway. In short, burglary is largely a crime of opportunity, and an unlocked door provides the opportunity. While expensive and complicated alarm systems provide a wide range of deterrence features, their cost and complexity will not prevent residential burglaries if the system is not activated. Even when properly used, no alarm system can effectively prevent burglaries. But if the alarm system is not activated at all (due to too many false alarms), or one of the doors is left inadvertently left unlocked, the likelihood of a burglary rises dramatically. 
   It has been proposed to provide a limited function, self-contained alarm unit for application to a door, for example, wherein the self-contained system includes arming circuitry, alarm sensor, and alarm sounding system all in a single housing. See, for example, U.S. Pat. Nos. 5,311,168; 6,078,256; and 6,950,033. Some of these door-mounted alarm systems may also integrate a door locking mechanism such that the alarm unit is armed when the door is locked and disarmed otherwise. Additionally, door lock systems exist that indicate to a potential burglar that the door is locked and the system is armed. However, these systems do not necessarily encourage the use of the system by the resident. Residents need a simple reminder and indicator of whether or not the door is locked. 
   SUMMARY OF THE INVENTION 
   The present invention encourages the use of a simple and effective burglary prevention device: the deadbolt lock. The present invention is a slipcover which covers the latch handle of an existing deadbolt lock system and signals to the resident when the deadbolt has been engaged. (Alternatively, the invention may also comprise a replacement latch handle incorporating the signal mechanism, or an entire deadbolt lockset that incorporates the signal mechanism into the latch handle; see below.) The slipcover includes a small, low-voltage user discernible signal, such as a light-emitting diode (LED), a liquid crystal display (LCD), a small light bulb, or any other type signal that can be toggled from an “off” position to an “on” position. In the present invention, the signal, which is incorporated into the deadbolt latch, toggles to the “on” position when the latch handle has been flipped to engage the deadbolt. The signal is powered by small batteries housed inside the slip cover. Once the latch handle is flipped to the locked position, the signal toggles to the “on” position, thus indicating to the resident that the deadbolt is engaged and the door is successfully locked. 
   Batteries are incorporated into the latch handle or slip cover to power the signal. A timer may also be incorporated into the circuitry so that the signal, when toggled to the “on” position by the closing of the deadbolt, toggles back to the “off” position after a set period of time. The timer allows the signal to remain in the “on” position for a pre-determined length of time sufficient for the resident to notice. This helps preserve battery life. If desired, the timer can be omitted. The timer and the signal are activated by a pressure-sensitive switch embedded in the slip-cover, and which is biased to toggle the signal between the “on” and “off” positions in response to the movement of the deadbolt latch handle between the locked and unlocked positions, respectively. 
   The design of the present invention is well suited for the elderly, the incapacitated, and those who live alone. The present invention is easy to install and easy to use, in contrast to much more complicated alarm systems. A resident can easily install the present invention on all of the doorways of the residence. Thus, when the doors are locked, a simple glance at each door will reveal that each signal is “on,” thus reminding the resident that the doors are locked. If one or more signals are still in the “off” position, this indicate to the resident that the deadbolt still needs to be engaged, and effectively reminds him to lock the doors. 
   The objects and advantages of the invention will appear more fully from the following detailed description of the preferred embodiment of the invention made in conjunction with the accompanying drawings. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top plan view of the present invention with batteries in an orientation parallel to the latch handle. 
       FIG. 2  is a side elevation view of the present invention. 
       FIG. 3  is a top view of the present invention showing a deadbolt latch handle according to the present invention affixed to a deadbolt mounting plate. 
       FIG. 4  is a perspective, exploded rendering of a preferred version of the present invention. 
       FIG. 5A  is a top plan view of the version of the invention depicted in  FIG. 4 . 
       FIG. 5B  is a vertical cross-section along line C-C of  FIG. 5A . 
       FIGS. 6A ,  6 B,  6 C,  6 D,  6 E are various views of the housing  12  as shown in  FIG. 4 .  FIG. 6C  is the top plan view;  FIG. 6A  is a cross-section through line A-A;  FIG. 6B  is a cross-section through line B-B;  FIG. 6D  is a left-side, vertical cross-section of  FIG. 6C ;  FIG. 6E  is a rear elevation view of  FIG. 6C . 
       FIG. 7  is a perspective rendering of the circuitry, batteries, and LED that are contained within the housing. 
       FIG. 8  is a circuit diagram illustrating how the LED  14  is energized by batteries  20  in response to motion of the handle body. 
   


   DETAILED DESCRIPTION 
   Throughout the drawings, the same reference numerals are used to denote the same features. 
     FIG. 1  is an schematic, top plan view of the present invention. In this view, the plane of the door to which the invention is mounted is in the plane of the paper. In this version of the invention, the housing  12  of the device is a slipcover, which is placed over the latch handle of an existing deadbolt door lock. The slipcover is preferably constructed of metal or metalized plastic and is dimensioned and configured to be slightly larger than the existing latch. Alternatively, the slip cover may be constructed from a flexible or elastic material so that the slipcover will fit snugly over the handle without any loose edges. The slipcover has an outside surface and an inside surface; see  FIG. 4 . The inside surface of the slipcover is next to the door and has an opening to receive the existing deadbolt latch handle.  FIGS. 1 and 2  illustrate that the outside surface has a visible signal  14  incorporated into the slip cover. As noted earlier, the signal  14  may be any type of signal, without limitation, that is dimensioned and configured to toggle between an “on” position and an “off” position. A light-emitting diode (LED) is preferred, but a small light bulb or LCD may also be used. The signal is preferably positioned distally from the rotational axis of the deadbolt latch handle. This is simply the preferred embodiment. The signal  14  may be disposed at any point on the surface of housing  12 . 
   The signal is attached to circuitry  16  securely contained within the slipcover. The circuitry operationally connects the signal  14  to a switch  18  for turning the signal on and off, at least one battery  20  to power the signal, and an optional timer  22 . 
   In the preferred version of the invention, the circuitry is configured so that the battery supplies power through the optional timer  22  to the signal  14  when the deadbolt is in the locked position. A switch  18  responsive to the rotation of the latch handle controls the power supply from the battery  20  to the timer  22 . When the deadbolt is locked, the switch is closed, and power flows from the battery, through the timer, and into the signal, thus turning it on. When the deadbolt is unlocked, the switch is opened, and the signal is turned off. Thus, the switch is activated when the latch handle is thrown to engage the deadbolt, which locks the door. 
   In the preferred embodiment, the switch  18  is a simple, pressure activated switch that responds to the rotational movement of the latch handle. Simple rotary switches are well known. Any other type of switch that is responsive to the rotation of the deadbolt latch handle may also be used, for example a magnetic switch, a mercury-type gravity switch, a gyroscopically-activated switch, a reed switch, etc. 
   As noted earlier, the invention may be configured in the form of a slip cover that fits over the latch of an existing deadbolt lockset. Another version of the invention is a replacement latch handle which attaches to an existing deadbolt lockset. The latch handle contains the signal and circuitry noted earlier. In this version of the invention, the conventional latch handle on an existing deadbolt lockset is removed, and a latch handle according to the present invention is inserted in its place. Alternatively, an original equipment manufacturer deadbolt latch set may be manufactured that includes the present invention directly incorporated into the latch. 
     FIG. 4  is a perspective, exploded rendering of a preferred version of the present invention. The back side of the housing is visible, as is frame  40  on which is anchored the batteries  20 , circuitry  16  (in the form of an integrated chip) and signal  15  (depicted as an LED).  FIG. 5A  is a top plan view of the invention depicted in  FIG. 4 , and  FIG. 5B  is a vertical cross-section along line C-C of  FIG. 5A . As can be best in  FIG. 5B , the frame  40  and its associated components, fits snugly within the housing  12 . The LED  14  is then visible through an aperture  14 ′ (see  FIG. 6C ) in the housing  12 . The frame  40  can be adhered within the frame by any mechanism known in the art, including friction, glue, solder, fasteners of any sort, etc. 
   Detailed views of the housing in isolation are provided in  FIGS. 6A ,  6 B,  6 C,  6 D,  6 E.  FIG. 6C  is the top plan view of the housing;  FIG. 6A  is a cross-section through line A-A;  FIG. 6B  is a cross-section through line B-B;  FIG. 6D  is a left-side, vertical cross-section of  FIG. 6C ;  FIG. 6E  is a rear elevation view of  FIG. 6C . Preferred dimensions (in inches) are provided. These dimensions are provided solely for purposes of illustration and are not limiting in any fashion. 
     FIG. 7  is a perspective rendering of the circuitry, batteries, and LED that are carried on frame  40 , which is ultimately contained within the housing. The frame  40  can be fabricated from any suitably stiff or semi-flexible material, typically plastic. The frame may also be a printed circuit board, in which case the required circuitry would be incorporated directly into frame  40  itself. A micro-chip  16  is provided to activate and deactivate signal  14  in response to the position of the housing. The position of the housing is sensed by reed switch  18 , which activates and deactivate the signal  14  in response to the position of the housing in which the frame is disposed. Batteries  20  are depicted within corresponding brackets  41  to hold them in place. 
     FIG. 8  is a circuit diagram illustrating how the LED  14  is energized by batteries  20  in response to motion of the handle body. The circuit is opened or closed via switches SW 1  (right side) and SW 2  (left side) in response to the position of the housing. The two arms of the reed valve  18  serve to open and close the circuit in response to the left or right orientation of the deadbolt lock to which the housing is attached. A microchip  16 ′, such as a pic10f206, may be used to control the status of the LED. The pic10f206 is a low-cost, high-performance, 8-bit, fully static, flash-based CMOS microcontroller. It employs a RISC architecture with only 33 single-word/single-cycle instructions. All instructions are single cycle (1 μs) except for program branches, which take two cycles. It is a preferred chip because of its easy-to-use and easy to remember instruction set reduces development time significantly. A host of other functionally equivalent microcontrollers may also be used. They can be obtained from a very large number of international suppliers, such as Microchip Technology Inc., Chandler, Ariz. 
   It is understood that the invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.