Apparatus for detect missing battery in smoke detector

• US 4,959,640 A
• Filed: 03/09/1989
• Issued: 09/25/1990
• Est. Priority Date: 03/09/1989
• Status: Expired due to Fees

• Current Assignee: Huafeng Electronics, Inc.
• Original Assignee: Pioneer Manufacturing Company Limited (Pioneer Corporation)
• Inventors: Hall, Thomas L.
• Primary Examiner(s): Crosland, Donnie L.
• Assistant Examiner(s): MULLEN, THOMAS J
• Application Number:
  US07/320,946
• Time in Patent Office: 565 Days
• Field of Search: 340/693, 340/628-630
• US Class Current: 340/693.7
• CPC Class Codes: G08B 29/181 due to failing power supply

Abstract

A battery-powered smoke detector in which the battery is inserted in a removable door that is then inserted into the detector to power the detector is rendered incapable of insertion into the smoke detector unless a battery is in place in the removable door. A spring-loaded door stop is moved by the spring into a position where it prevents the door from being inserted into the smoke detector. A pin in the female terminal of the door that engages the male terminal of the battery is forced away from the door stop by a spring. When the door stop is depressed manually and a battery is inserted into the terminals, the pin is forced by the male terminal of the battery into a latching position in the door stop, holding it in a position where it will not interfere with insertion of the door. The absence of a door provides warning to an observer that the battery-powered smoke detector is not operable for lack of a battery.

Claims

1. An apparatus for providing visible indication of absence of a battery from a battery-powered smoke detector having an insertable door that holds a battery, the apparatus comprising:

a. a stop;

b. a stop spring disposed to engage the stop so as to exert a force that maintains the stop in a position that prevents insertion of the door into the smoke detector

c. means for latching a stop into a position that permits insertion of the door into the smoke detector; and

d. means for operating the means for latching upon insertion of a battery into a pair of terminals in the door.

2. The apparatus of claim 1 wherein the means for latching comprises:

(a) a pin that projects through a female terminal in a first position and that engages the spring-loaded stop so as to latch the stop in a second position that compresses the stop spring and maintains the stop in a position that permits insertion of the door into the smoke detector; and

(b) a pin spring that is disposed to apply a force causing the pin to project through the female terminal and thus assume the first position an d that is compressed when the pin is caused to assume the second position to latch the stop.

3. The apparatus of claim 2 wherein the means for operating the means for latching comprises a male terminal of a battery that engages the pin to move the pin from the first position to the second position that latches the stop and permits insertion of the door when the battery is inserted into the female terminal.

4. In a smoke detector having a removable door that supports the battery and a set of male and female terminals affixed to the door, supporting the battery, and connecting the battery to the smoke detector to power the smoke detector, the improvement comprising:

(a) a spacer affixed to the door and including a guide slot;

(b) a sop having a tang insertable in the guide slot and movable with respect to the spacer so that the tang slides in the guide slot, the stop also including an aperture and a projection capable of preventing insertion of the door into the smoke detector in a first position and permitting insertion of the door in a second position;

(c) a spring disposed to maintain a spring force between the stop and the door to hold the stop in the first position if a battery is not connected to the terminals;

(d) a pin having an axis that is coaxial with an axis of the female terminal and movable on the axis so as to be free of the aperture in the stop in a first pin position and to engage the aperture in the stop in a second pin position, the pin projecting from the female terminal in the first position such that insertion of the battery into the battery terminals when the stop is moved to place the axis of the aperture into alignment with the axis of the pin presser the pin into the aperture to hold the stop in the second position and thereby permit insertion of the door into the smoke detector.