DOUBLE-BEARING POSITION ENCODER FOR NON-INVASIVE PHYSIOLOGICAL MONITORING

• US 20180238718A1
• Filed: 12/19/2017
• Published: 08/23/2018
• Est. Priority Date: 07/17/2013
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Dalvi, Cristiano
• Granted Patent: US 11,022,466 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: G01D 11/02 Bearings or suspensions for moving parts
• CPC Class Codes: G01D 5/34738 Axles; Driving or coupling means

Abstract

A double-bearing position encoder has an axle stabilized within a housing via two bearings disposed on opposite walls of the housing. The axle is in communications with a rotating cam. The cam actuates a pulser so as to generate an active pulse at a tissue site for analysis by an optical sensor. The axle rotates a slotted encoder wheel or a reflective encoder cylinder disposed within the housing so as to accurately determine the axle position and, hence, the active pulse frequency and phase.

Claims

1. A double-bearing position encoder has an axle stabilized within a housing via bearings disposed on opposite walls of the housing, the axle is in communications with a rotating cam that actuates a pulser so as to generate an active pulse at a tissue site for analysis by an optical sensor, the axle rotates a slotted encoder wheel or a reflective encoder cylinder so as to accurately determine the axle position and, hence, the active pulse frequency and phase, the double-bearing position encoder comprising:

a housing;

a pair of bearings disposed within opposite facing walls of the housing;

an axle disposed within the housing and supported by the bearings,

the axle in mechanical communications with a pulser;

an encoder wheel fixedly attached to the axle and having a plurality of wheel slots;

an LED disposed within the housing that illuminates the encoder wheel; and

a detector responsive to the LED illumination after optical interaction with the wheel slots as the axle rotates the wheel so as to indicate the wheel position.

2. The encoder according to claim 1 further comprising an encoder mask having a plurality of mask slots disposed over an edge and along both sides of the encoder wheel so that the LED illumination passes through the mask slots and the wheel slots before reaching the detector.

3. The encoder according to claim 2 wherein the encoder mask is folded so that LED light is reflected off of the mask a first time before illuminating the encoder wheel and second time before reaching the detector.

4. The encoder according to claim 2 wherein the encoder mask is folded so that LED light is not reflected off of the mask before illuminating the encoder wheel and before reaching the detector.

5. An encoding method for determining the position of a rotatable axle comprising:

rotatably mounting an encoder wheel on a double-bearing-mounted axle;

folding an encoder mask proximate an outer edge of the encoder wheel;

disposing a plurality of wheel slots around the encoder wheel proximate the outer edge;

disposing a plurality of mask slots through the encoder mask; and

disposing an emitter and a detector proximate to and on either side of the encoder wheel so that light intermittently passes through the encoder wheel via the wheel slots and the mask slots.

6. The encoding method according to claim 5 further comprising reflecting light from the emitter off of the mask at least once before it reaches the detector.

7. The encoding method according to claim 6 further comprising reflecting light from the emitter off of the mask at least twice before it reaches the detector.

8. The encoding method according to claim 5 further comprising directly illuminating the detector from the emitter without reflection off the mask.

9. An optical encoder that indicates the position of a rotatable axle comprising:

a double bearing means of stabilizing a rotatable axle within an encoder housing;

an encoder wheel means fixedly mounted to the axle so as to rotate as the axle rotates;

an illumination and detection means of intermittently passing light through the encoder wheel means as it rotates; and

a folded and slotted mask means of precisely passing light through encoder wheel.