Light-Emitting Toothbrush With Optical Drive Shaft and Sealed Contacts
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Solution Overview
Problem
Existing electric toothbrush designs face challenges with the integration of light-emitting technology due to space constraints, increased brush head size, and unreliable electrical connections, which can lead to water exposure and damage.
Innovation Solution
A light-emitting toothbrush design where the light source is located in the handle and projects light through a moving optical light guide within the drive shaft to the brush head, using a specialized connector for the brush head that also acts as an optic ferrule, and incorporates electrical sensing through a conductive path in the toothbrush head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the light source and electronics are located inside the brush head, then light emission function is achieved, but the brush head size increases making it uncomfortable for users
Solution Approach 1:
The light source and controlling electronics are extracted from the brush head and relocated to the handle. The handle contains the light source, control circuitry, and power management components. The brush head receives only the mechanical drive shaft and electrical contacts, significantly reducing its size and weight while maintaining the light emission function through optical coupling.
Solution Approach 2:
The optical light guide is nested within or alongside the mechanical drive shaft in the handle. The light guide travels through the drive shaft to deliver light to the brush head, allowing dual functionality (mechanical transmission and optical transmission) within the same structural envelope, thereby avoiding additional space requirements.
2Ease of operation
If press fit electrical connections are used for replaceable brush heads, then ease of replacement is achieved, but reliability deteriorates due to water exposure, electrical shorts, and damage from electrolysis
Solution Approach 1:
A specialized connector assembly acts as an intermediary between the handle and brush head. This connector includes sealed electrical contacts, waterproof gaskets, and alignment features that prevent water ingress and electrical shorts while maintaining easy attachment and detachment. The connector design eliminates direct press-fit connections that are prone to failure.
Solution Approach 2:
The connector assembly performs multiple functions simultaneously: electrical connection, mechanical attachment, waterproof sealing, and optical alignment. By integrating these functions into a single universal connector, the design achieves both ease of replacement and high reliability without requiring separate mechanisms for each function.
3Power
If the drive shaft is used solely for mechanical power transmission, then mechanical function is optimized, but space efficiency deteriorates as separate light transmission path is needed
Solution Approach 1:
The drive shaft is designed to serve dual purposes: mechanical power transmission from the motor to the brush head and optical light transmission from the handle to the brush head. The light guide is positioned within or adjacent to the drive shaft, allowing both functions to coexist in the same spatial envelope, thereby improving space efficiency without compromising mechanical performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces brush head size, enhances reliability, and ensures safe and efficient electrical connections, while allowing for therapeutic blue light emission and effective sensing of the toothbrush head in the mouth.
Implementation Method 1
a light guide contained in or comprising the core of the drive shaft
Implementation Method 2
the light is diffusely reflected by the chassis of the white replacement brush head through a transparent or translucent brush head containing tufts of transparent or semi-transparent bristles
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
An electric toothbrush includes a handle with a motor and a light source located in a proximal end. A brush head is in a distal end of the toothbrush, and a drive shaft conveys kinetic energy from the motor to the brush head. The drive shaft includes a light guide from the light source to the distal end and contains two layers of an optical medium of differing refractive indices to enable TIR within the light guide. The brush has a tuft plate having bristles and is made of a polymer such that the water contact angle of the tuft plate is less than 90 degrees and is at least partially transparent. The handle and the tuft plate have electrical contacts to make a contact sensor and a movement sensor provides movement data. A computing device processes movement and contact data to determine when to activate the light.