referring to fig1 and 2 , electric toothbrush 10 is shown to consist of handle section 12 , stem 14 , brush guard 15 and rotary brush 16 . handle section 12 which does not form any part of the invention contains a reversible motor powered by a rechargeable battery or other suitable power source ( not shown ) and actuated by switch 18 so that brush 16 may operate in either a clockwise or counter - clockwise direction . obviously the battery does not have to be rechargeable . located on the top of handle 12 is a tapered conical stem housing receiving portion 20 best seen in fig2 . conical drive member 22 is connected to the motor driven shaft in the housing of the handle ( not shown ) and has provided thereon flanges 24 . housing portion 26 of stem 14 is shaped to press - fit over stem housing receiving portion 20 of handle 12 . stem housing 14 and brush guard 15 are formed from molded plastic as an integral element provided with internal annular ribs 28 , 30 , and 32 , as best seen in fig3 . positioned on the interior of stem housing 14 and shown in fig4 is a shaft 33 . in the preferred embodiment , shaft 33 consists of two main shaft sections 34 and 36 . it is understood that a single shaft may be provided as explained in greater detail below . the bottom end 35 of shaft section 34 is constructed to fit over conical member 22 and has on the interior thereof slotted receiving grooves 38 to accommodate flanges 24 . with bottom end 35 of shaft section 34 interconnected with conical member 22 , a driving connection is established such that rotation of member 22 causes rotation of shaft section 34 . located on the upper end of shaft section 34 are flanges 40 . shaft section 36 is constructed with base portion 42 having aligned axial grooves 44 shaped to slidingly receive flanges 40 of shaft section 34 so that the rotation of shaft section 34 will cause rotation of shaft section 36 . adjacent the base portion 42 is an enlarged portion 46 having an annular recess 48 . at the top of shaft section 36 is an enlarged portion 52 constructed to physically mate with portion 54 of rotary brush 16 so that when portion 52 is interlocked with portion 54 rotation of shaft section 36 will cause rotation of brush 16 . brush guard 15 has a member 58 constructed to mate with portion 56 of rotary brush 16 to provide rotational support for brush 16 . it is understood that the interlocking of portions 52 and 54 and portions 56 and 58 may be of any suitable design and does not form a part of the invention . the important feature is that the brush 16 is removably and rotatably interconnected at its top to the brush guard housing and removably and rotatably interconnected to be driven by the shaft section 36 . referring to fig5 control knob 60 is shown from a top plan view as including handle portion 62 , neck 64 , and arms 66 . control knob 60 is used to control and to maintain shaft section 36 in one of two desired positions , namely , a brush lock , or raised position and a brush removal position . the control knob 60 is positioned with neck 64 traversing an opening 68 of stem housing 14 and arms 66 lying in annular recess 48 of the shaft 36 . opening 68 as best seen in fig6 is in the shape of an inverted l and includes a vertical slot 70 and horizontal slot 72 having a ledge 74 . the vertical slot permits vertical movement of shaft 36 relative to shaft 34 and the ledge 74 provides a raised lock position . since the raised position is the operating position of shaft 36 , groove 44 must be long enough to accommodate the axial or vertical motion while maintaining a driving relationship with shaft 34 . with the electric rotary toothbrush 10 assembled , shaft sections 34 and 36 are located in the interior of stem housing 14 . annular rib 28 serves to keep shaft section 34 in axial alignment with shaft section 36 and conical member 22 . annular ribs 30 and 32 serve to maintain shaft section 36 in axial alignment with brush 16 and shaft section 34 . control knob 60 is inserted in opening 68 of stem 14 such that arms 66 fit into annular recess 48 . flanges 24 of conical member 22 is accomodated in grooves 38 of shaft section 34 to provide a driving relationship with the motor . the operation of electric rotary toothbrush 10 and control knob 60 fully assembled can be explained as follows . with control knob 60 in the raised and locked position shown in fig1 the neck 64 is located in horizontal slot 72 of opening 68 and rests locked on ledge 74 . arms 66 of control knob 60 is in annular recess 48 and maintains shaft section 36 in a raised position . portion 52 of shaft section 36 is maintained in its mated condition with portion 54 of brush 16 and portion 56 of brush 16 is maintained in its mated condition with portion 58 of brush guard 15 . flanges 40 of shaft section 34 is maintained in the lower interlocking portion of grooves 44 of shaft section 36 . actuation of switch 18 causes rotation of conical member 22 , shaft sections 34 and 36 and rotary brush 16 . with control knobs 60 in the position discussed above , shaft 36 is maintained in its raised and lock position . brush 16 is thus provided with rotational support on both ends thereof at portions 54 and 56 . further , there is no possibility of inadvertent removal of brush 16 due to the positive interconnection of portion 52 of shaft section 36 with portion 54 of the brush and the interconnection of portion 56 of the brush with portion 58 of the guard 15 . when it is desired to remove brush 16 , control knob 60 is manually rotated so that neck 64 is first slid horizontally toward the vertical slot 70 and then in a downward direction so that at the end of its travel control knob 60 is positioned at the bottom of vertical slot 70 . the downward movement of control knob 60 results in arms 66 causing shaft section 36 to move downward . grooves 44 of shaft section 36 ride on flanges 40 of shaft section 34 such that at the end of the downward movement of shaft section 36 flanges 40 are positioned in the upper portion of respective grooves 44 . it should be appreciated that the flanges 40 are always positioned in grooves 44 so that when control knob 60 is returned to its original position shown in fig1 a driving connection between flanges 40 and grooves 44 is maintained . with the control knob 60 positioned such that neck 64 is on the bottom of vertical slot 70 , shaft section 36 is lowered so that the brush portion 56 becomes disconnected with portion 58 of guard 15 . similarly , the guard housing is designed with shouler 59 to retain the bottom of the toothbrush so that the lowering of the shaft section 36 disconnects shaft portion 52 and rotary brush portion 54 so that the brush can be easily removed . it is evident that another brush of the same size and configuration can replace brush 16 if it is so desired . in an alternative embodiment of the invention ( not shown ) shaft 33 may be a single piece . in that instance , an equivalent to control knob 60 and the associated structure of enlarge portion 42 can be located at the lower end of the proposed single shaft . conical member 22 and its associated flanges 24 can be modified to be the functional equivalent of flange 40 of shaft section 34 . also , control knob 60 and enlarged portion 42 may be at the center of the single shaft if desired . the two - piece drive shaft is preferred because the brush can be easily removed without disassembly of the toothbrush guard from the handle and because the parts which are moved during brush insertion and removal and thus the parts most susceptible to wear are the easily replaceable two - piece drive shaft and not its connection with the motor . thus , the most inexpensive part wears first . this is a substantial advantage over prior art systems . from the preceding description of the preferred embodiments , it is evident that the objects of the invention are attained in that a rotary electric toothbrush is provided in which the brush has rotational support at both ends of its axis and can be easily removed without disassembly of the toothbrush housing . although the invention has been described and illustrated in detail , it is to be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation . the spirit and scope of this invention are to be limited by the terms of the appended claims .
an electric rotary toothbrush having an integral stem and brush guard housing within which is an axially moveable brush drive shaft and a removable brush . the brush drive shaft is manually controlled for axial movement by a control knob located on the stem and brush guard housing to lock the brush so that it is rotatably mounted on both sides thereof within the stem and brush guard housing and to allow removal of the brush from the housing .