Temperature alarm

• US 4,864,283 A
• Filed: 01/23/1989
• Issued: 09/05/1989
• Est. Priority Date: 06/30/1986
• Status: Expired due to Term

• Current Assignee: Tandem Computers Incorporated (HP Inc.)
• Original Assignee: Tandem Computers Incorporated (HP Inc.)
• Inventors: Seto, Kan-Chiu
• Primary Examiner(s): Swann, III, Glen R.
• Assistant Examiner(s): MULLEN, THOMAS J
• Application Number:
  US07/300,160
• Time in Patent Office: 225 Days
• Field of Search: 340/584-588, 340/593-594, 340/502-503, 340/815, 340/22, 340/693
• US Class Current: 340/584
• CPC Class Codes: G01P 1/106 by comparing the time duration between two impulses with a reference time
• CPC Class Codes: G01P 13/00 Indicating or recording presence, absence, or direction, of movement electric switches H01H; counting moving objects G06M7/00

Abstract

A temperature alarm includes a thermostat for actuating an audible alarm, a control panel-mounted LED and a circuit board-mounted LED. The audible alarm, once actuated by the thermostat, can be temporarily disabled by the user by actuating a disable timer connected to the audible alarm. After a period of time the timer times out to return control of the audible alarm to the thermostat. The panel LED is illuminated continuously while the chosen temperature value is exceeded. The circuit board LED is mounted to a circuit board within the equipment housing. Once illuminated by the thermostat, the circuit board LED remains actuated regardless of the temperature to provide an indication to a service technician that the chosen temperature was exceeded since the last servicing. The circuit board-LED, coupled to a latching relay also mounted to the circuit board, is extinguished by manually resetting the latching relay.

Claims

1. A temperature alarm for use with equipment of the type having a housing with an external display panel and a user-inaccessible region therein, the alarm comprising:

a power source;

a temperature-sensitive element, coupled to the power source, for providing a temperature signal when the temperature at said element is past a chosen value;

alarm means, coupled to the temperature-sensitive element, for providing an audible alarm when the temperature-sensitive element provides the temperature signal;

first visual indicator means, coupled to the temperature-sensitive element, for providing the user a visual indication at the display panel that the temperature is past the chosen value;

a user-actuated alarm disable means at the display panel, coupled to the alarm means, for selectively temporarily disabling the alarm means for a period of time and thereafter re-enabling said alarm means; and

a second visual indicator means, housed within the housing at the user-inaccessible region, coupled to the temperature-sensitive element and the power source, for continuously providing a second visual indication once the temperature-sensitive element has provided the temperature signal, the second visual indicator means including a user-actuated reset means for resetting the second visual indicator means so to halt the provision of the second visual indication after the temperature-sensitive element is no longer providing the temperature signal;

the visual indication provided by the first and second visual indicator means being independent of whether the alarm means is selectively temporarily disabled by the user-activated alarm disable means.