Dental cleaning appliance

Abstract

A nozzle (126) for a dental cleaning appliance is described. The nozzle comprises a nozzle chamber, the nozzle chamber having an internal dimension (ND); an inlet (200) for coupling to a liquid reservoir, the inlet having an inlet dimension (ID) along an inlet plane (P3) at an entrance to the nozzle chamber, orthogonal to an inlet axis (CI) of the nozzle chamber; and an outlet (1261) through which working fluid is ejected, the outlet having an outlet dimension (OD) along an outlet plane (L2a) at an exit from the nozzle chamber, orthogonal to an outlet axis (A1) of the nozzle chamber. The internal dimension, (ND) is on an inner plane (IP) spaced from and parallel to the outlet plane and is larger than the outlet dimension (OD) and the nozzle chamber comprises an internal surface (1262) which converges between the inner plane and the outlet plane, towards the outlet, and wherein a ratio of the outlet dimension (OD) to the internal dimension (ND) is in the range of 0.2-0.4. A dental cleaning appliance (1) comprising the nozzle is also described.

Description

[0001] DENTAL CLEANING APPLIANCE

[0002] BACKGROUND

[0003] Dental cleaning appliances, such as toothbrushes, for use in treating oral cavities of users are known. Some dental cleaning appliances have a stem portion attached to a brush head, with cleaning elements, such as tufts of bristles, projecting from a front side of the brush head. Some oral treatment devices have a handle integrally formed with the stem portion. Others are configured to be removably attachable to a handle, for instance so that the handle is usable with several different oral treatment devices.

[0004] SUMMARY

[0005] A first aspect of the present invention provides a nozzle for a dental cleaning appliance, comprising: a nozzle chamber, the nozzle chamber having an internal dimension; an inlet for coupling to a liquid reservoir, the inlet having an inlet dimension along an inlet plane, at an entrance to the nozzle chamber, orthogonal to an inlet axis of the nozzle chamber; and an outlet through which working fluid is ejected, the outlet having an outlet dimension, along an outlet plane, at an exit from the nozzle chamber, orthogonal to an outlet axis of the nozzle chamber, wherein, the internal dimension is on an inner plane spaced from and parallel to the outlet plane, and is larger than the outlet dimension, and the nozzle chamber comprises an internal surface which converges between the inner plane and the outlet plane, towards the outlet, and wherein a ratio of the outlet dimension to the internal dimension is in the range of 0.2-0.4.

[0006] The nozzle is configured to deliver a jet of working fluid, such as water, to an oral cavity of a user of a dental cleaning appliance. The jet of working fluid from such a nozzle is suitable for jetting interproximal spaces. With the ratio of the outlet dimension to the internal dimension in the range of 0.2 - 0.4, a large jet cone can be achieved, increasing the probability of the jet hitting the interproximal space between two teeth. This ratio further helps achieve an even pressure distribution across the diameter of the cone shaped jet formed. Hence, the energy of the fluid (and potential impact zone on the teeth) at the edge and at the centre of the jet’s diameter is similar. The jet can thus hit the interproximal space with sufficient energy to dislodge any plaque and / or food particles.

[0007] The internal dimension may in some examples refer to a largest internal dimension of the nozzle chamber, such as a height dimension of the nozzle chamber, or a diameter of the nozzle chamber in examples where the nozzle chamber has a circular cross section (when viewed from the front side, as in Figure 5).

[0008] The inlet axis is generally centred on the inlet. In some examples, the inlet is circular. The outlet axis is generally centred on the outlet. In some examples, the outlet is circular.

[0009] The inlet plane and the outlet plane are positioned at respective leading faces of the inlet and outlet. In some examples, the outlet plane and the inlet plane are orthogonal.

[0010] Optionally, the outlet dimension is in the range of 0.5mm to 1.5mm. The outlet dimension determines the size of the jet of working fluid. The jet of working fluid should be suitably compact to perform its function (e.g. cleaning interproximal spaces) while not being bothersome to the user of the dental cleaning appliance, for example by generating excess fluid.

[0011] Optionally, the inlet axis is substantially orthogonal to the outlet axis.

[0012] Optionally, the inner plane is parallel to and coincides with the inlet axis and there is an offset distance from the inner plane to the outlet plane, such that a ratio of the offset distance to the inlet dimension is between 1.5 and 2.

[0013] Minimising the offset distance has been shown to improve performance of the dental cleaning device and the nozzle. In some examples, the offset distance is about 2.5mm.

[0014] Optionally, the outlet has a collar region having a width in the range of range of 0.30mm to 0.60mm. In some examples, the collar region width is about 0.45mm. Optionally, the internal surface converges from a second nozzle chamber plane, which is parallel to and between the inner plane and the outlet plane, to a first nozzle chamber plane, which is parallel to and between the second nozzle chamber plane and the outlet plane.

[0015] Optionally, the collar region extends from the outlet plane to the first nozzle chamber plane.

[0016] Optionally, the internal surface converges with a convergence angle in the range 60 degrees to 120 degrees. In some examples, the convergence angle is approximately 90 degrees.

[0017] Optionally, the inlet dimension is in the range of 1mm to 3.5mm. In some examples, the inlet dimension is about 1.5mm.

[0018] A second aspect of the present invention provides a dental cleaning appliance comprising a nozzle for delivering a working fluid to the oral cavity of a user, the nozzle comprising: a nozzle chamber, the nozzle chamber having an internal dimension; an inlet for coupling to a liquid reservoir, the inlet having an inlet dimension along an inlet plane at an entrance to the nozzle chamber, orthogonal to an inlet axis of the nozzle chamber; and an outlet through which working fluid is ejected, the outlet having an outlet dimension, along an outlet plane, at an exit from the nozzle chamber, orthogonal to an outlet axis of the nozzle chamber; wherein, the internal dimension is on an inner plane spaced from and parallel to the outlet plane, and is larger than the outlet dimension, and the nozzle chamber comprises an internal surface which converges between the inner plane and the outlet plane, towards the outlet, and wherein a ratio of the outlet dimension to the internal dimension is in the range of 0.2- 0.4.

[0019] Optionally, the nozzle may be located on a spigot of the dental cleaning appliance.

[0020] Optionally, the outlet dimension is in the range of 0.5mm to 1.5mm.

[0021] Optionally, the inlet axis is substantially orthogonal to the outlet axis. Optionally, the inner plane is parallel to and coincides with the inlet axis and there is an offset distance from the inner plane to the outlet plane, such that a ratio of the offset distance to the inlet dimension is between 1.5 and 2.

[0022] Optionally, the outlet has a collar region having a width in the range of range of 0.30mm to 0.60mm.

[0023] Optionally, the internal surface converges from a second nozzle chamber plane, which is parallel to and between the inner plane and the outlet plane, to a first nozzle chamber plane, which is parallel to and between the second nozzle chamber plane and the outlet plane.

[0024] Optionally, the collar region extends from the outlet plane to the first nozzle chamber plane.

[0025] Optionally, the internal surface converges with a convergence angle in the range 60 degrees to 120 degrees.

[0026] Optionally, the inlet dimension is in the range of 1mm to 3.5mm.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 shows a perspective view of an example of an electrically powered toothbrush having an attachment with a brush head of the electrically powered toothbrush removably attached to a handle of the electrically powered toothbrush.

[0029] Figure 2 shows a side view of the toothbrush of Figure 1.

[0030] Figure 3 shows a partial perspective exploded view of the toothbrush of Figure 1, in which the attachment with the brush head has been detached from the handle.

[0031] Figure 4 shows a partial close-up perspective view of a spigot of the toothbrush of Figure 1.

[0032] Figure 5 shows a partial close-up view of the attachment of the toothbrush of Figure 1. Figure 6 shows a partial cross-sectional view of the attachment of Figure 5, with the crosssection being along a plane containing the central longitudinal axis of the attachment, and orthogonal to a plane formed by a length and a width of the attachment.

[0033] Figure 7 shows a partial cross-sectional view of the attachment of Figure 5, with the crosssection being offset from a central longitudinal plane of the attachment.

[0034] Figure 8 shows a partial cross-sectional view of the spigot of Figure 4, with the cross section being along a plane containing the central longitudinal axis, and along the width of the attachment.

[0035] Figure 9 shows a detailed view of a nozzle of the spigot of Figure 4.

[0036] DETAILED DESCRIPTION

[0037] The Figures show a dental cleaning appliance 1 in the form of an electrically powered toothbrush. The toothbrush 1 comprises a handle 10 and a brush head attachment 20 that is shaped and sized to be attachable to, and thereafter detachable from, the handle 10. The attachment 20 comprises a brush head 40. The brush head 40 is for use in brushing an oral cavity of a user of the toothbrush 1. The attachment 20 is replaceable by, or interchangeable with, another attachment (not shown), so that the handle 10 may be used with several attachment portions successively. Successive attachments may be the same or different (e.g. for different kinds of cleaning). In alternative examples, the attachment 20 is integral with the handle.

[0038] The attachment 20 comprises a neck portion 50 with an elongate body and the brush head 40 is attached to the neck portion 50 at a distal end of the elongate body. The neck portion 50 has a length SL and a width SW perpendicular to the length SL. The brush head 40 has a heel end 41 that is proximal to the neck portion 50, an opposite toe end 42 that is distal from the neck portion 50 and that defines a first end 21 of the attachment 20. The neck portion 50 extends from the heel end 41 of the brush head 40 in a longitudinal direction and is narrower than the brush head 40 in a lateral direction over a majority of the length SL of the neck portion 50. The neck portion 50 has a first end 51 that is proximal to the brush head 40 and an opposite second end 52 that is distal from the brush head 40 and flared. The flared second end 52 of the neck portion 50 defines a second end 22 of the attachment 20 opposite to the first end 21 of the attachment 20, and also defines a first interface 23 by which the attachment 20 engages with the handle 10. The first interface 23 is a cavity, or bore, for receipt of a second interface 13 of the handle 10, as is described in more detail below. A central longitudinal axis CL is defined along the length SL, centred on the cavity 23. The brush head 40 comprises cleaning elements 60, in the form of flexible bristle tufts in this example.

[0039] The neck portion 50 has a front side 510, or leading side or face, which is on a same side as the cleaning elements 60 of the brush head 40. The neck portion 50 comprises an aperture 710 and an optically transparent cover 720 in this front side 510. The aperture 710 and the transparent cover 720 are offset from each other in the longitudinal direction of the neck portion 50. The aperture 710 is closer to the first end 21 of the attachment 20 and is a circular aperture or hole. The transparent cover 720 is closer to the second end 22 of the attachment 20 and is a transparent window through which visible light (or other, non-visible wavelengths of light) is passable during use of the toothbrush 1. The purposes of the aperture 710 and the transparent cover 720 are explained below.

[0040] Discussion will now briefly turn to the handle 10 of the toothbrush 1. The handle 10 is an elongate structure comprising a grip portion 110 and a spigot 120 attached to the grip portion 110. The grip portion 110 has a first end 111 that is proximal to the spigot 120 and an opposite second end 112 that is distal from the spigot 120 and that defines a first end 11 of the handle 10. The spigot 120 extends from the first end 111 of the grip portion 110 in a longitudinal direction of the handle 10 and is narrower than the grip portion 110 in a lateral direction orthogonal to the longitudinal direction of the handle 10. The spigot 120 has a first end 121 that is proximal to the grip portion 110 and an opposite second end 122 that is distal from the grip portion 110. The second end 122 of the spigot 120 defines a second end 12 of the handle 10 opposite to the first end 11 of the handle 10, and the spigot 120 is the second interface 13 for engaging with the first interface 23 of the attachment 20. More specifically, the spigot 120 is insertable into the cavity 23, or bore, of the first interface 23 of the neck portion 50 of the attachment 20, to engage the spigot 120 with the attachment 20 and thereby releasably connect the attachment 20 to the handle 10. As shown in Figs. 1 and 3, when the handle 10 is engaged with the attachment 20, the attachment 20 together with the spigot 120 forms the stem portion 30 of the toothbrush 1, where this stem portion 30 extends from the grip portion 110 of the handle 10.

[0041] The grip portion 110 of the handle 10 has an outer housing 113. Inside the outer housing 113, the handle 10 has a reservoir 25 for storing water, a pump 26, a controller 27 and a battery 28. The spigot 120 of the handle 10 has a housing 123 comprising a body 124 and an optically transparent window 125 attached to the body 124 on one lateral side of the handle 10.

[0042] Inside the housing 123 of the spigot 120, the handle 10 has a sensor in the form of a camera 29 located relative to the transparent window 125 so that a conical field of view 220 of the camera 29 includes part of the environment external to the handle 10 that is visible to the camera 29 through the transparent window 125.

[0043] The pump 26, the controller 27 and the camera 29 are electrically connected to the battery

[0044] 28 by electrically conductive wires (not shown), so as to be electrically powered by the battery 28. The camera 29 is for capturing images of the user’s oral cavity during use of the toothbrush 1, when the attachment 20 is connected to the handle 10. Moreover, the camera

[0045] 29 is communicably connected to the controller 27 by electrically conductive wires (not shown), via which the camera 29 is configured to send data representative of the captured images to the controller 27. The spigot 120 has a nozzle 126 with an opening (or outlet) 1261 on the same lateral side of the spigot 120 as the transparent window 125, that is on the same leading side or face of the brush head 40. When the attachment 20 is engaged with the handle 10, the opening 1261 of the nozzle 126 overlaps with the aperture 710 of the neck portion 50 of the attachment 20 to form the exit orifice 1261 / 710 of the nozzle 126. The pump 26 is for pumping the water from the reservoir 25 to the nozzle 126 so that the water passes through the nozzle 126 as a jet during use of the toothbrush 1. A jet cone 210 is defined which is capable of being jetted by the nozzle. The jet cone 210 has a cone angle of approximately 25 degrees in this example and can in other examples be in the range 20 degrees to 40 degrees.

[0046] The transparent window 125 and the nozzle 126 are offset from each other in the longitudinal direction of the handle 10. The nozzle 126 is closer to the second end 12 of the handle 10 than the transparent window 125. The camera 29 and the nozzle 120 are offset, or spaced apart, from each other in the longitudinal direction by a distance LI defined from a central axis Al of the nozzle to the central axis A2 of the camera. The distance LI is 4.5mm in this example and can in other examples be in the ranges 3.5mm to 5.5mm, or 4mm to 4.5mm, where a smaller distance LI may be beneficial in certain instances, as will be described.

[0047] A jetting region 230 is created at an intersection / overlap of the jet cone 210 with the field of view 220 of the camera 29, and includes a depth determined between a lower setback limit L and an upper setback limit U, as explained below. The jetting region 230 corresponds to a region which may be both sensed by the camera and jetted by the nozzle concurrently. In other words, the camera can image objects (i.e. teeth) at least when the objects are within the lower and upper setback limits U, L. The jetting region 230 is also determined by a distance L2, which corresponds to the separation of the exit orifice 1261 / 710 of the nozzle 126 and a leading surface of the camera 29 along a depth dimension, which is orthogonal to the leading side or face of the brush head 40. The exit orifice 1261 / 710 of the nozzle 126 defines a first plane L2a (extending into the page in Figure 6), which is parallel to a central longitudinal axis CL of the spigot. In addition, the leading surface of the camera 29 defines a second plane L2b (also extending into the page in Figure 6), which is parallel to, and further from the central longitudinal axis CL of the spigot 120 than the plane L2a of the nozzle 126. The camera 29 is approximately aligned with a base of the bristles 60, while the nozzle’s 126 exit orifice 1261 / 710 is recessed by the distance L2. The distance L2 may be in the range of 1mm to 1.5mm. The distance L2 is approximately 1.22mm in this example.

[0048] As indicated, the jetting region 230 extends between bounds determined by the lower setback limit L and upper setback limit U. The lower and upper setback limits, L, U, can also be viewed as parallel planes (extending into the page in Figure 6), which are parallel to planes L2a and L2b. The lower and upper setback parallel planes may be referred to as a minimum setback plane L and a maximum setback plane U. The area between the lower and upper setback limits L, U is where the jetting can occur while the brush head is in contact with a tooth, and approximately extends between a guard 800(between the nozzle 126 and the bristles 60) and a tip of the bristles 60 when fully extended. In other words, the minimum setback plane L is aligned with a front edge of the guard 800 and the maximum setback plane U is aligned with a tip of the bristles 60 when the bristles 60 are fully extended. In this example, the separation of the lower setback and the upper setback L, U is the distance L3 and is about 4mm. In this example, the minimum setback plane L is 6 mm from the first plane L2a and the maximum setback plane U is at least 10 mm from the plane L2a.

[0049] It is desirable to maximise an area of the jetting region 230, the area being that which can be imaged by the camera, at the intersection with the jet cone 210 and within the lower and upper setback limits, L, U. The area of the jetting region 230 increases as the distance LI is decreased, with a linear relationship with a negative gradient of approximately 5 at a given setback distance L3, i.e. an increase in distance LI by 1mm results in a reduction of a number of pixels imaging the jetting region 230 by 5. The number of pixels imaging the jetting region 230, in this example, is about 50. Therefore, it is desirable to, within physical and optical constraints, minimise the distance LI. The area of the jetting region 230 will vary for other examples, for example based on the various dimensions, spacings and a pitch and number of pixels in the camera (or other sensor). Generally, though, the area of the jetting region 230 tends to be larger when the distance LI is reduced. The area of the jetting region 230 may range from 12mm2to 18mm2(orthogonal to the plane of the page in Figure 6).

[0050] When the attachment 20 is connected to the handle 10, the nozzle 126 is aligned with the aperture 710 of the attachment 20, and the camera 29 and the transparent window 125 of the handle 10 are aligned with the transparent cover 720 of the attachment 20. The controller 27 is configured to perform an analysis of the data it receives from the camera 29 in use. The controller 27 is also configured to cause the pump 26 to pump the water from the reservoir 25 and through an inlet 200 to the nozzle 126 (and thus through the aperture 710) towards the user’s oral cavity, when the controller 27 determines, based on the analysis, that the nozzle 126 and the aperture 710 are aligned with a part of the oral cavity that is to be cleaned, such as an interdental space.

[0051] The guard 800 (which projects from the front side 410 of the head portion 40 at a location between the aperture 710 and the bristle tufts 60, and between the transparent cover 720 and the bristle tufts 60) helps to shield the aperture 710 and the transparent cover 720 from liquids or objects that could potentially obscure the aperture 710 and the transparent cover 720. The efficacy of the jetting of the oral cavity may be reduced if the aperture 710 and / or the transparent cover 720 are obscured, for example by bending bristle tufts 60 or by excess slurry.

[0052] During use of the toothbrush 1, the attachment 20 is attached to the handle 10 by way of the user inserting the spigot 120 of the handle 10 into the cavity 23, or bore, of the attachment 20. This causes the aperture 710 and the transparent cover 720 of the attachment 20 to respectively align with the nozzle 126 and the camera 29 and transparent window 125 of the handle 10. The user then applies dentifrice to the bristle tufts 60 and brushes their teeth and gums with the bristle tufts 60 and dentifrice.

[0053] Alignment of the attachment 20 and the spigot 120 is assisted by alignment features or datums. A first datum DI is defined by an end surface of the spigot 120, which is an accurately defined distance from central axes Al and A2. A second datum D2 is defined by an internal surface of the attachment 20, the internal surface facing the first datum DI and being an accurately defined distance relative to the transparent cover 720 and the aperture 710. The two datums, DI, D2, come into contact with one another, and thereby control the degree of insertion of the spigot 120 when the attachment 20 is attached to the handle 10, to ensure that the axis Al is accurately aligned with the aperture 710 and axis A2 is accurately aligned with the transparent cover 720.

[0054] Other locations for the datum are envisaged, in other examples. For example, the datums could be provided in other locations on the spigot and within the brush head attachment, or even the base of the brush head attachment and the leading face of the handle could act as respective datums. In any event, the datums ensure accurate longitudinal alignment between the spigot and brush head attachment. The advantage of the datum location described above arises from manufacturing variation, since the nominal distance from the datum to the camera is minimised, the error in this dimension will have a minimal value compared to other locations.

[0055] The attachment 20 and the spigot 120 are fixed in place via engagement features on them. In particular, the spigot 120 includes a plurality of rails along its side (not shown in the figures) and the attachment 20 includes corresponding recesses to engage the rails. Such engagement helps to minimize the relative movement between the spigot 120 and the attachment 20. Radial (sliding) and tangential (rotation) motion are substantially prevented, to ensure alignment of features described. However, other engagement features as known to those skilled in the art may be used.

[0056] Further, a plurality of sealing elements may be provided between the attachment 20 and the spigot 120. Leakage of fluid jetted from the nozzle 126, slurry, saliva and other fluids into the gap between the attachment 20 and the spigot 120 can be reduced or prevented by these sealing elements. Preventing leakage into the gap is also important to prevent obscuration by fluid or fogging, and for sanitary reasons.

[0057] To allow the camera 29 to detect images of the teeth, an LED 250 is provided as a source of light to illuminate teeth of a user in use. A light pipe 260 is arranged to guide or direct light emitted by the LED 250 into the field of view 220 of the camera 29, while preventing undesirable internal reflections from occurring. The light pipe 260 may be integrally formed with the transparent window 125 of the spigot as shown in Fig. 7. As shown in Fig. 8, the light pipe 260 and the LED 250 are arranged laterally (in the SW direction) next to the camera 29, with the light pipe 260 arranged between the LED 250 and the optically transparent cover 720 of the attachment 20 (in the direction orthogonal to the SW and SL directions). The light pipe 260 guides light from the LED 250 through the optically transparent window 125, the optically transparent cover 720 and towards teeth of a user in use. The camera 29, the LED 250 and the light pipe 260 collectively define a sensor arrangement. During the brushing, the camera 29 captures images of the user’ s teeth and interdental spaces and sends data representative of the images to the controller 27. The controller 27 analyses the data and causes the pump 26 to be electrically connected to the battery 28, so that the pump 26 pumps water from the reservoir 25 and through the nozzle 126 (and thus through the aperture 710) towards the user’s oral cavity, when the controller 27 determines that the nozzle 126 and the aperture 710 are aligned with a part of the oral cavity that is to be cleaned, such as an interproximal (interdental) space, when within the jetting region 230. This facilitates cleaning of the oral cavity.

[0058] The nozzle 126 is shown in detail in Figure 9. The nozzle 126 is connected to the water reservoir 25 via the inlet 200, as previously explained. The nozzle 126 comprises a nozzle chamber with an internal dimension (diameter) ND of 3.5mm. The inlet 200 is a cylindrical channel, with a central axis / inlet axis CI. The inlet 200 has an inlet dimension (cross sectional diameter) ID of about 1.5mm along an inlet plane P3, where the inlet plane P3 is located at a leading face of the inlet 200 and at an entrance to the nozzle chamber, orthogonal to the inlet axis CI. The internal dimension ND of the nozzle chamber is defined along an inner plane IP which is parallel to and spaced away from an outlet plane (which coincides with the above-mentioned first plane L2a and the outlet 1261 of the nozzle 126). In this example, the inner plane IP coincides with the central axis CI of the inlet 200. The outlet

[0059] 1261 of the nozzle 126 is offset from the axis CI by an offset distance OO of 2.5mm (from the inner plane IP to the outlet plane L2a). The nozzle chamber comprises an internal surface

[0060] 1262 which converges between the inner plane IP and the outlet plane L2a, towards the outlet 1261. The inner surface 1262 converges, in this example, from a second nozzle chamber plane P2, which is parallel to and between the inner plane IP and the outlet plane L2a, to a first nozzle chamber plane Pl, which is parallel to and between the second nozzle chamber plane P2 and the outlet plane L2a. In this example, the second nozzle chamber plane P2 is located at 0.25mm from axis CI and the first nozzle chamber plane Pl is located at 2.05mm from the axis CI in a direction towards the outlet 1261. A contraction angle / convergence angle 0 may be defined as the angle at which the internal surface 1262 converges. In one example, the contraction angle is 90° but the contraction angle may range from 60° to 120° in other examples. The nozzle 126 extends as a circular channel, or a collar region, for a length OL between the outlet plane L2a and the first nozzle chamber plane Pl. The length OL is 0.45mm in one example but can range from 0.3mm to 0.6mm in other examples. The outlet 1261 has an outlet dimension / diameter OD, which is along the outlet plane L2a at an exit from the nozzle chamber. The outlet dimension OD is orthogonal to an outlet axis of the nozzle chamber (the outlet axis of the nozzle chamber being orthogonal to the inlet axis CI). In this example, the outlet dimension OD is 0.9mm.

[0061] The internal dimension ND of the nozzle chamber is larger than the outlet dimension OD of the outlet 1261. A contraction ratio may be defined, wherein the contraction ratio is OD / ND and is in the range of 0.2 to 0.4 in examples. In some examples, the outlet dimension / diameter OD may be in a range of 0.5mm to 1.5mm. In some examples, a ratio of OO / ID is between 1.5 to 2. In some examples, the contraction / convergence angle 0 is between 60° and 120°.

[0062] The nozzle is configured to deliver a jet of fluid with pressure up to 1500kPa. The inlet flow velocity is up to lOm / s.

[0063] Whilst particular examples have been described, it should be understood that these are illustrative examples only and that various modifications may be made without departing from the scope of the invention as defined by the claims. For example, in some other examples, the dental cleaning appliance, such as a toothbrush, comprises a handle grip portion integrally formed with a stem portion (comprising the spigot and the brush head). In some examples, the dental cleaning appliance has one or more cleaning elements, in the form of bristle tufts, projecting from the front side of the brush head, wherein the arrangement of the bristle tufts is different to that shown in the attached Figures. In some examples, the dental cleaning appliance has only one cleaning element, which may or may not be in the form of a bristle tuft, projecting from the front side of the brush head In some examples, the stem portion of the dental cleaning appliance has a neck portion that extends from a head portion of the stem portion in a first direction and is not narrower than (e.g., is of equal width to) the head portion in a lateral direction orthogonal to a first direction. In some examples, the camera may be replaced by another sensor to sense interdental spaces. In some examples, the camera to nozzle separation distances LI and / or L2 may differ to the above-described values. In some examples, the setback separation distance L3 may differ to the one described above. In some examples, the jetting cone may have a different cone angle to the one described above. In some examples, the sensor arrangement may not comprise one or more of the LED and the light pipe.

Claims

CLAIMS1. A nozzle for a dental cleaning appliance, comprising: a nozzle chamber, the nozzle chamber having an internal dimension; an inlet for coupling to a liquid reservoir, the inlet having an inlet dimension along an inlet plane, at an entrance to the nozzle chamber, orthogonal to an inlet axis of the nozzle chamber; and an outlet through which working fluid is ejected, the outlet having an outlet dimension, along an outlet plane, at an exit from the nozzle chamber, orthogonal to an outlet axis of the nozzle chamber, wherein, the internal dimension is on an inner plane spaced from and parallel to the outlet plane, and is larger than the outlet dimension, and the nozzle chamber comprises an internal surface which converges between the inner plane and the outlet plane, towards the outlet, and wherein a ratio of the outlet dimension to the internal dimension is in the range of 0.2- 0.4.

2. The nozzle according to claim 1, wherein the outlet dimension is in the range of 0.5mm to 1.5mm.

3. The nozzle according to any one of the preceding claims, wherein the inlet axis is substantially orthogonal to the outlet axis.

4. The nozzle according to any one of the preceding claims, wherein the inner plane is parallel to and coincides with the inlet axis and there is an offset distance, from the inner plane to the outlet plane, such that a ratio of the offset distance to the inlet dimension is between 1.5 and 2.

5. The nozzle according to any one of the preceding claims, wherein the outlet has a collar region having a width in the range of range of 0.30mm to 0.60mm.

6. The nozzle according to claim 5, wherein the internal surface converges from a second nozzle chamber plane, which is parallel to and between the inner plane and the outletplane, to a first nozzle chamber plane, which is parallel to and between the second nozzle chamber plane and the outlet plane.

7. The nozzle according to claim 6, wherein the collar region extends from the outlet plane to the first nozzle chamber plane.

8. The nozzle according to any one of the preceding claims, wherein the internal surface converges with a convergence angle in the range 60 degrees to 120 degrees.

9. The nozzle according to any one of the preceding claims, wherein the inlet dimension is in the range of 1mm to 3.5mm.

10. A dental cleaning appliance comprising a nozzle for delivering a working fluid to the oral cavity of a user, the nozzle comprising: a nozzle chamber, the nozzle chamber having an internal dimension; an inlet for coupling to a liquid reservoir, the inlet having an inlet dimension, along an inlet plane, at an entrance to the nozzle chamber, orthogonal to an inlet axis of the nozzle chamber; and an outlet through which working fluid is ejected, the outlet having an outlet dimension, along an outlet plane, at an exit from the nozzle chamber, orthogonal to an outlet axis of the nozzle chamber, wherein, the internal dimension is on an inner plane spaced from and parallel to the outlet plane, and is larger than the outlet dimension, and the nozzle chamber comprises an internal surface which converges between the inner plane and the outlet plane, towards the outlet, and wherein a ratio of the outlet dimension to the internal dimension is in the range of 0.2- 0.4.

11. The dental cleaning appliance according to claim 10, wherein the outlet dimension is in the range of 0.5mm to 1.5mm.

12. The dental cleaning appliance according to claim 10 or claim 11, wherein the inlet axis is substantially orthogonal to the outlet axis.

13. The dental cleaning appliance according to any one of claims 10 to 12, wherein the inner plane is parallel to and coincides with the inlet axis and there is an offset distance from the inner plane to the outlet plane, such that a ratio of the offset distance to the inlet dimension is between 1.5 and 2.

14. The dental cleaning appliance according to any one of claims 10 to 13, wherein the outlet has a collar region having a width in the range of range of 0.30mm to 0.60mm.

15. The dental cleaning appliance according to any one of claims 10 to 13, wherein the internal surface converges from a second nozzle chamber plane, which is parallel to and between the inner plane and the outlet plane, to a first nozzle chamber plane, which is parallel to and between the second nozzle chamber plane and the outlet plane.

16. The dental cleaning appliance according to claim 15, wherein the collar region extends from the outlet plane to the first nozzle chamber plane.

17. The dental cleaning appliance according to any one of claims 10 to 16, wherein the internal surface converges with a convergence angle in the range 60 degrees to 120 degrees.

18. The dental cleaning appliance according to any one of claims 10 to 17, wherein the inlet dimension is in the range of 1mm to 3.5mm.

Images