Electric toothbrush assembly

An improved electric toothbrush assembly including a handle and a brush portion. The handle has an output shaft which is provided with a vertical positioning rod. The brush portion includes a brushing housing, a brush cover, a brush rod received between the brush housing and brush cover, and two brush heads. The brush housing is coupled to the handle as well as the brush cover. The housing is provided with a brush face formed with two parallel elongated face slots. The brush cover is provided with a cover pin projecting from a middle section thereof. The brush rod has hooks at a bottom side thereof, a vertical elongated slot near a middle section thereof and two grooves at an upper side thereof corresponding to the brush face of the brush housing. The brush heads are each provided with brush axles received therein which pass through the grooves of the brush rod and the face slots of the brush housing. The hooks of the brush rod engage the positioning rod of the handle. The cover pin passes through the slot of the brush rod. When the output shaft of the handle performs linear movement, it will bring the brush rod to reciprocate in a linear direction while the brush heads displace inwardly and outwardly respectively in relation to the brush face when the brush axles move along the grooves of the brush rod.

BACKGROUND OF THE INVENTION 
(a) Field of the Invention 
The present invention relates to an improved toothbrush assembly, and more 
particularly to a toothbrush assembly in which brush heads respectively 
displace inwardly and outwardly when a brush rod is brought by an output 
shaft to reciprocate in a linear direction. 
(b) Description of the Prior Art 
A conventional electric toothbrush operates by means of a direct current 
motor output which translates rotation of the motor into a reciprocating 
movement to drive a brush head that, due to the reciprocating movement, 
rotates to brush the teeth of the user. An example of such toothbrushes is 
disclosed in U.S. Pat. No. 5,727,273 for "Electric Toothbrush Assembly 
with Sterilizing and Charging device" to the inventor of the present 
invention. 
It has been found that brushing should be done in an up-and-down direction, 
not left-and-right, and the rotation of the brush head is not proper for 
up-and-down brushing. Improvement on the prior art is therefore necessary. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to provide an improved 
toothbrush assembly in which two brush heads displace inwardly and 
outwardly respectively when a brush rod is driven by an output shaft to 
reciprocate in a linear direction, thus eliminating the drawback with the 
prior art and ensuring oral hygiene.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, the improved electric toothbrush assembly 
according to the present invention essentially comprises a handle 1, and a 
brush portion 2. 
The handle 1 has an interior accommodating therein a battery, a motor, and 
a transmission device which causes a distal output shaft to perform linear 
up-and-down movements. As such a structure is well known in the art, e.g., 
the above-mentioned U.S. Pat. No. 5,727,273, it will not be discussed in 
detail herein. The difference between the handle 1 of the present 
invention and that of the prior art is that a position rod 12 is 
vertically insertably provided on an output shaft 11 projecting from an 
uppermost part of the handle 1 for connecting the brush portion 2 for 
operation purposes. 
The improvement provided by the present invention resides in the brush 
portion 2. As shown, the brush portion 2 includes a brush housing 21, a 
brush cover, and a brush rod 23 sandwiched between the brush housing 21 
and the brush cover, two brush heads 24, and a coupling ring 25. 
The brush housing 21 has a cylindrical portion at a lower side which is 
sized to match the coupling ring 25 and has a bottom edge that may be 
recessed or projecting for purposes of engagement with the handle 1. The 
brush housing 21 is also provided with engagement means such as pins and 
grooves at an upper side and lateral sides thereof adapted for coupling 
with the brush cover 22. In addition, the brush housing 21 includes a 
brush face 211 at the upper side, the brush face 211 is provided with two 
parallel elongated face slots 212 for passage of brush axles 241 of the 
brush heads 24. At the same time, in order that friction or wear between 
the brush face 211 and the brush head 24 may be reduced or slowed down, a 
face cover 213 having two parallel elongated holes 214 corresponding to 
the face slots 212 of the brush face 211 is fitted to a front side of the 
brush face 211. The opposite side of the brush face 211 also has a back 
cover 215 having two parallel elongated holes 216 corresponding to the 
face slots 212 and the elongated holes 214 fitted thereto to reduce wear. 
The size and shape of the brush cover 22 match those of the brush housing 
21 so that they may be coupled together. The brush cover 22 includes a 
cover pin 221 extending horizontally from a middle section thereof to 
serve as a pivot during up-and-down movement of the brush rod 23. Like the 
brush housing 21, the brush cover 22 is provided with engagement means 
such as pins and grooves at its peripheries for coupling with the brush 
housing 21. 
The brush rod 23 is a flat elongated structure so that it may be sandwiched 
between the brush housing 21 and the brush cover 22. It includes two hooks 
231 at both sides of a bottom side thereof respectively for engaging the 
positioning rod 12 of the handle 1. The hooks 231 are oppositely oriented 
and preferably have an oblique angle to enhance the firmness of the 
engagement. The brush rod 23 further includes a vertical elongated slot 
232 at the center near its upper side. The size of the slot 232 is 
slightly greater than that of the cover pin 221. The upper side of the 
brush rod 23 corresponding to the brush face 211 is provided with two 
hollowed out grooves 233 that are obliquely arranged and oriented in 
different directions for passage of the brush axles 241 of the brush heads 
24. 
The brush heads 24 are each a substantially square structure with curved 
outer edges. The two brush axles 241 are secured in respective insert 
holes 242 of the brush heads 24. In addition, an outer side of each brush 
head 24 is provided with a plurality of non-through holes 243 in which 
bundles of bristles 244 (see FIG. 2) may be planted in position. 
Furthermore, in order to resist wear, the brush axles 241 may be fitted 
with respective sleeves 245. 
The coupling ring 25 is sized to match the upper edge of the handle 1 and 
the bottom portion of the brush housing 21 so that it may be coupled 
thereto. And to ensure water tightness, the coupling ring 25 is coupled 
thereto by supersonic waves. The coupling ring 25 is actually optionally. 
The handle 1 and the brush housing 21 may be configured to have a longer 
length and are directly coupled using supersonic waves. 
Referring to FIG. 2, in assembly, the brush rod 23 is received in the space 
between the brush housing 21 and the brush cover 22, with the brush axles 
241 passing through the grooves 233 to couple to the brush head 24. The 
hooks 231 of the brush rod 23 are fastened to the positioning rod 12 of 
the output shaft 11 of the handle 1 such that the brush head 24 and the 
bristles 244 thereon are exposed on the outside. 
Referring to FIGS. 3 and 4, the brush portion 2 and the handle 1 are 
firstly coupled. If the output shaft 11 is located at a low position, it 
shows that the positioning rod 12 is not yet connected to the brush rod 
23. At this point, by turning on the power of the handle 1 to cause the 
output shaft 11 to displace up and down, the positioning rod 12 will, 
during the process of displacement of the output shaft, move along the 
inclination of the hooks 231 to engage with the hooks 231, synchronously 
bringing the brush rod 23 to displace up and down. Therefore, when the 
brush rod 23 is at a highest point as shown in FIG. 3, the two brush axles 
241 will be at lowest points of the respective grooves 233. And at this 
time, the two brush heads 24 are roughly located on the brush face 211. 
But when the brush rod 23 displaces downwardly, the brush axles 241 move 
along the grooves 233 to slidably displace upwardly and outwardly so that 
the brush heads 24 also slidably displace outwardly. In this way, the 
electric toothbrush of the present invention performs horizontal brushing 
movements, the brush heads 24 will respectively move upwardly and 
downwardly at a high speed. This is healthy brushing meeting the 
requirements of oral hygiene. 
Compared to the prior art, the present invention enabling the bristles to 
move both upwardly and downwardly during brushing provides a vast 
improvement. 
Although the present invention has been illustrated and described with 
reference to the preferred embodiment thereof, it should be understood 
that it is in no way limited to the details of such embodiment but is 
capable of numerous modifications within the scope of the appended claims.