Transducers

• US 4,091,803 A
• Filed: 02/09/1976
• Issued: 05/30/1978
• Est. Priority Date: 02/17/1975
• Status: Expired due to Term

• Current Assignee: Thomas Orr
• Original Assignee: Thomas Orr
• Inventors: Pinder, Russell Stuart
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Cohen, Lee S.
• Application Number:
  US05/656,842
• Time in Patent Office: 841 Days
• Field of Search: 128/2.05 P, 128/2.05 T, 128/2.05 E, 128/2.05 R, 128/2.05 V, 128/2 L, 338/15, 357/30, 356/39-41
• US Class Current: 600/479
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: G04B 47/061 calculating scales for indicating relationship between quantity and time indicating or recording of quantity-time ratios G01D; meters for measuring average speed, measuring speed by chronograph G01P; slide rules and calculating wheels G06G

Abstract

A transducer for optically detecting a cyclic phenomenon of variable frequency and supplying an electric signal corresponding to the frequency, comprises a light source for illuminating the site of the phenomenon and a detector for detecting variations in the level of light reflected from the site of the phenomenon and providing the required electric signal, the detector being a semiconductor opto-electronic cell and the light source being positioned within the detector.

Claims

1. A transducer for detecting heartbeats and supplying an output signal in dependence thereon with a frequency component of the output signal corresponding to a heartbeat rate to be detected, said transducer comprising a light emitting diode and a planar opto-electronic detector which is a photo-conductive cell encircling said light emiting diode and which comprises an electrically insulating substrate, an insulating film on said substrate, a photo-voltaic PN junction on the surface of said insulating film comprising a layer of cadmium sulfide and an annular disc of cuprous sulfide on the surface of said layer of cadmium sulfide to provide a light sensitive surface layer, first and second output terminals, conductor means connecting each of said output terminals to a respective one of said layers, the transducer adapted to be mounted on a watch case component means positionable adjacent the skin of a user with the light emitting diode facing the skin of the user to emit light thereagainst being energizable by a periodic signal from a source contained in said watch case component means, the light emitting diode being positioned when in use to emit light toward a surface of skin tissue of a user to transilluminate said surface of skin tissue to cause the surface of skin tissue to emit light and the opto-electronic detector encircling said light emitting diode so as to be positioned in close proximity to said surface of skin tissue so that the majority of light originating from said light emitting diode emitted from said surface of skin tissue is directed into said opto-electronic detector which detects variations in the reflected light level from said surface of skin tissue and provides said output signal to said first and second output terminals in response to changes in arterial blood flow.

2. A transducer positionable adjacent the skin of a user to detect heartbeats and provide an electric signal the frequency of which corresponds to heartbeat rate, the transducer comprising a light source positioned adjacent the skin of the user to transilluminate an area of said skin tissue and detector means for detecting variation in the reflected light level from the skin tissue so as to produce an electric signal responsive to changes in arterial blood flow, said light source comprising a light emitting diode having power input leads connectible to a source of periodic input signals accommodated in a watch housing, the light emitting diode being positioned centrally within said detector means, the detector means comprising of an opto-electronic cell, said cell including an electrically insulating substrate, an insulating film on said insulating substrate, a photo-voltaic PN junction formed on said insulating film, said PN junction including a layer of cadmium sulfide on said insulating film and an annular disc of cuprous sulfide on the surface of said layer of cadmium sulfide to provide a light sensitive surface layer, first and second output terminals, means defining electrically conductive paths on said insulating film on said substrate for connecting each of said terminals to a respective one of said layers.

3. A transducer according to claim 2, wherein said light emitting diode emits light having a wavelength in the range of 600 to 650 nm.