Fire detector

• US 5,568,130 A
• Filed: 09/30/1994
• Issued: 10/22/1996
• Est. Priority Date: 09/30/1994
• Status: Expired due to Fees

• Current Assignee: Ernest A. Dahl
• Original Assignee: Ernest A. Dahl
• Inventors: Dahl, Ernest A.
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): GOINS, DAVETTA WOODS
• Application Number:
  US08/312,946
• Time in Patent Office: 753 Days
• Field of Search: 340/630, 340/555, 340/629, 340/632, 340/628, 250/574
• US Class Current: 340/630
• CPC Class Codes: G08B 17/103 using a light emitting and receiving device
• CPC Class Codes: G08B 17/113 Constructional details

Abstract

An apparatus for detecting fire including a light source for generating light, a light sensor for receiving light from the light source and providing an analog signal representing the intensity of the received light, and a clear plastic light guide for transmitting the light from the light source to the sensor. The light guide include notches for allowing smoke to enter the notches. Smoke entering the notches decreases the intensity of the light passing therethrough. A calibration sensor is included. The sensitivity of the fire detector is increased by a lens assembly which collimates the light generated by the light source. The color of smoke entering the light guide may be determined by generating colored light. Temperature, humidity and carbon monoxide levels are also detected and the information is integrated with the smoke detection data to provide a reliable fire detector.

Claims

1. An apparatus for detecting the amount of smoke in an environment, comprising:

a slender, straight, enclosing light guide having a length, a first end and a second end, said light guide being unapertured along its length, said light guide including a first lengthwise linear array of notches and a second lengthwise linear array of notches, each said notch having two clear notch sides which provide therebetween an inwardly recessed interspace for said environment;

a light source, at said first end, for generating a light beam, said light beam having an initial light intensity, said light beam subsequently passing through said notch sides and said inwardly recessed interspaces of said first lengthwise array of notches;

a first reflector, at said second end, for reflecting said light beam which has previously passed through said notch sides and said inwardly recessed interspaces of said first lengthwise array of notches;

a second reflector, at said second end, for reflecting said light beam which has previously been reflected by said first reflector, said light beam subsequently passing through said notch sides and said inwardly recessed interspaces of said second lengthwise array of notches;

a light sensor, at said first end, for receiving said light beam, said light beam having previously passed through said notch sides and said inwardly recessed interspaces of said second lengthwise array of notches, said light beam having an attenuated light intensity, said light sensor generating an analog signal which indicates said attenuated light intensity, said initial light intensity having been reduced to said attentuated light intensity in proportion to the amount of said smoke through which said light beam has passed in said inwardly recessed interspaces of said first lengthwise array of notches and said second lengthwise array of notches.

2. The apparatus of claim 1, further comprising a calibration sensor for receiving said light beam of said initial light intensity and generating an analog signal which indicates said initial light intensity, thereby permitting calibration of said light sensor by comparison of said initial light intensity with respect to said attenuated light intensity.

3. The apparatus of claim 1, wherein said light source generates light selected from the group of light types consisting of infrared light and visible light.

4. The apparatus of claim 1, wherein said light source further comprises means for receiving electrical power.

5. The apparatus of claim 4, wherein said (the) means for receiving electrical power is for receiving (receives) DC power, such that said light beam generated by said (the) light source is steady.

6. The apparatus of claim 5, wherein said (the) means for receiving electrical power is for receiving (receives) pulsed power, such that said light beam generated by said (the) light source is pulsed.

7. The apparatus of claim 1, wherein each said notch has two said notch sides which are parallel to each other.

8. The apparatus of claim 1, wherein each said notch has two said notch sides which meet at a junctional edge of said notch sides so as to form an angle.

9. The apparatus of claim 1, further comprising at least one lens assembly for collimating said light beam generated by said light source, whereby the sensitivity of said apparatus is increased.

10. The apparatus of claim 9, wherein each said lens assembly includes two lenses, and each said notch is coupled with a said lens assembly whereby one said lens is coupled with one said notch side.

11. The apparatus of claim 1, further comprising means for determining a color of said smoke through which said light beam passes in said inwardly recessed interspaces of said first lengthwise array of notches and said second lengthwise array of notches.

12. The apparatus of claim 11, wherein said means for determining a color of said smoke comprises means, associated with said light source, for generating colored light.

13. The apparatus of claim 1, further comprising means for sensing properties of said environment which are selected from the group of properties consisting of relative humidity, ambient temperature and carbon monoxide level.

14. The apparatus of claim 1, further comprising:

at least one lens assembly for collimating said light beam generated by said light source; and

a calibration sensor for receiving said light beam of said initial light intensity and generating an analog signal which indicates said initial light intensity, thereby permitting calibration of said light sensor by comparison of said initial light intensity with respect to said attenuated light intensity.

15. The apparatus of claim 14, wherein said light source generates light selected from the group of light types consisting of infrared light and visible light.

16. A device for sensing, and which can be suitably used for monitoring, the amount of smoke in an environs, said device comprising:

a hollow, slender, transparent member which is symmetrical with respect to an imaginary longitudinal axis and is impenetrable to smoke, said member having a first end, a second end, an exterior surface and an interior surface, said member having on opposite sides of said longitudinal axis a first axial alignment of depressions and a second axial alignment of depressions, each said depression having a recessed exterior surface area and a raised interior surface area, each said recessed exterior surface area defining an exterior interstice which smoke from said environs can enter;

a light source, located at said first end of said member, for emitting a light beam which travels in the axial direction toward said second end, along said first axial alignment of depressions, so as to hug said interior surface and traverse each said exterior interstice of said first axial alignment of depressions;

a dual reflector, located at said second end of said member, for redirecting said light beam to travel in the axial direction toward said first end, along said second axial alignment of depressions, so as to hug said interior surface and traverse each said exterior interstice of said second axial alignment of depressions; and

a light sensor, located at said first end of said member, for providing analog signals corresponding to the intensity of said light beam, said analog signals being a function of the diminution of said intensity of said light beam, said diminution being a function of the amount of smoke from said environs which is present in said light beam in said exterior interstices.

17. A device for sensing the amount of smoke as in claim 16, wherein said light sensor is a first light sensor and further comprising a second light sensor, located proximate said light source, for providing analog reference signals corresponding to said intensity of said light beam in the absence of said diminution.

18. A device for sensing the amount of smoke as in claim 16, further comprising at least one pair of lenses, each said pair of lenses coupled with a said depression for collimating said light beam.

19. Apparatus for sensing the amount of atmospheric particles, comprising:

an elongated chamber which is surrounded by an exterior region and which surrounds an interior region, said chamber having a first end section, a second end section and a transparent continuous longitudinal section, said longitudinal section having a first longitudinally aligned series of inward indentations and a second longitudinally aligned series of inward indentations, said first series of indentations and said second series of indentations being substantially opposed, each said indentation having two indentation sides which bound a portion of said exterior region, said indentation sides longitudinally separating portions of said exterior region and said interior region;

a light source, positioned at said first end section, for emitting a light beam which will consecutively travel three substantially linear light paths, said light paths consecutively being a first longitudinal light path, a transverse light path and a second longitudinal light path, said first longitudinal light path passing through said indentation sides and said portions of said exterior region and said interior region along said first series of indentations, said second longitudinal light path passing through said indentation sides and said portions of said exterior region and said interior region along said second series of indentations;

a first obliquely angled reflector, positioned at said second end section, for reflecting said light beam which has traveled said first longitudinal light path so as to travel said transverse light path;

a second obliquely angled reflector, positioned at said second end section, for reflecting said light beam which has traveled said transverse light path so as to travel said second longitudinal light path; and

a light sensor, positioned at said first end section, for measuring the intensity of said light beam which has traveled said second longitudinal light path, said intensity being a function of the amount of atmospheric particles in said exterior region which have entered said light beam at said portions of said exterior region while said light beam has traveled said first longitudinal light path and said second longitudinal light path.

20. Apparatus for sensing the amount of smoke as in claim 19, wherein said light sensor is a first light sensor and further comprising a second light sensor, located near said light source, for measuring the intensity of said light beam in said first longitudinal light path before said light beam has reached a said indentation side.