Patent Description:
Insertion endoscopes are well-known devices in the medical field for visually examining the interior of a hollow organ or cavity of a body, such as lungs or a bladder or intestines, by means of inserting an insertion cord of the endoscope. The insertion cord of the endoscope comprises an elongated insertion tube, a distal tip part, and a bending section connecting the insertion tube with the distal tip part. The endoscope typically has a handle connected to the insertion tube and positioned at the proximal end as seen from the operator. The endoscope further has a vision device, such as a built-in camera or fibre optics. The vision device is typically incorporated in the distal tip part at the distal end of the endoscope. This definition of proximal as being closest to an operator and distal as being furthest from an operator is used throughout this disclosure. Illumination of the area in front of the distal tip part of the endoscope is normally required, in particular in the field of vision of the vision device. One known way of achieving such illumination is to incorporate one or more Light-Emitting Diodes (LEDs) in the distal tip part of the endoscope. Alternatively, illumination may be provided by light guides and/or fibre optics for guiding light from a light source outside the endoscope and to the distal tip part.

The bending section is provided in order to manoeuvre the endoscope inside the body cavity. The bending section has increased flexibility, e.g. achieved by a number of articulated segments of which the distal tip part forms the distalmost segment. Bending or straightening of the bending section in the insertion part of the endoscope is typically done by tensioning or slacking, respectively, steering wires running from the distal tip part through the remainder of articulated segments and along the inside of the elongated insertion tube to a control device, such as a control lever, of the endoscope handle.

Data and/or power cables for the vision device (when comprising a camera or image sensor) and other electronics, such as LED lighting accommodated in the distal tip part, also run along the inside of the elongated insertion tube and the bending section from the endoscope handle to the distal tip part. Furthermore, a working channel may run along the inside of the insertion tube and the bending section from the handle to the distal tip part, e.g. allowing liquid to be removed from the body cavity or allowing the insertion of medical tools or surgical instruments into the body cavity.

A main function of the endoscope handle is to allow precise manoeuvring of the distal tip part. Therefore, it is advantageous that the control of the steering wires can be tested and validated before being accommodated within shell parts of the endoscope handle.

Furthermore, the experience from an operator's point of view of manoeuvring of the distal tip part is sensitive to the alignment between the control device and the shell parts. In practice, manufactured parts are subject to tolerances and do not necessarily fit perfectly. For example, when the control device comprises a body accommodated within the shell parts and a control lever extending through a cut out of the shell parts, a misalignment of the body may cause the control lever to drag along a side of the cut out causing unnecessary friction. Furthermore, tighter tolerances increase manufacturing costs.

<CIT> discloses a handle for endoscope including a handle housing, an operating member accommodated in said handle housing, at least one guide tube adapted for surrounding and supporting at least one pull wire, and an anchoring block.

On this background, it may be seen as an object of the present disclosure to provide an endoscope handle allowing testing of the performance of one or more steering wires attached thereto prior to the complete assembly. Another object of the present disclosure is to provide an endoscope handle with a reduced tendency to misalignment of the control device relative to shell parts of the endoscope handle. Yet another object of the present disclosure is to provide an endoscope handle that can be manufactured to looser tolerances while maintaining a good alignment of the control device.

One or more of these objects may be met by aspects of the present disclosure as described in the following.

A first aspect of the invention as defined in claim <NUM> relates to an endoscope handle for an endoscope for visually inspecting inaccessible places, such as human body cavities, the endoscope handle comprising:.

Ideally, the shell parts match exactly (thus ensuring that the first and second column axes coincide). However, in practice, the parts of the handle are subject to manufacturing and assembly tolerances. Therefore, the dimensions of the handle components will vary. This may, in some cases, cause a slight misalignment between the shell parts and thus result in the column axes not coinciding exactly. Such misalignment may tip a plane of rotation of the control device relative to the shell parts and result in undesirable increased friction when operating the control device.

The inventors have found that retaining the trunnions of the control device between the columns of the shell parts may advantageously reduce or even eliminate said tip of the plane or rotation of the control device relative to the shell parts. Accordingly, pivoting the control device may be subject to lower friction. This may be especially advantageous when the endoscope comprises a working channel for tool insertions, as such inserted tools typically significantly increase the required torque for steering the distal tip of the endoscope.

Additionally or alternatively, the frame and the bearings may be formed as single component, preferably formed in a single piece of a polymer material. Preferably the polymer material allows adhesion by an adhesive. Preferably and adhesive curable by ultraviolet light, and the polymer material may preferably be transparent to ultraviolet light. One preferred polymer material is methyl methacrylate acrylonitrile butadiene styrene (MABS).

Additionally or alternatively, the frame may be formed by an injection moulding process. Preferably, the frame is a monolithic component that may be formed by a single shot injection moulding process. The frame could also be formed in a multi-shot injection moulding process, such as a two-component injection moulding process.

Additionally or alternatively, the control device may be formed as a single monolithic component, preferably by injection moulding.

Additionally or alternatively, the first and second columns of the shell parts may clamp the trunnions of the control device between the columns of the shell parts.

In practice, the components of the handle are subject to manufacturing and assembly tolerances. Therefore, some manufactured components may exhibit undesirable clearances that may cause unwanted sounds, such as rattling, during use. Although typically not the case, such undesirable sounds may be interpreted as the presence of faults. However, by arranging the columns of the shell parts to clamp the trunnions there in-between, such undesirable clearances between the handle components may be significantly reduced to avoid such unwanted sounds.

Additionally or alternatively, each trunnion may extend partly through the respective bearing and may mate with the respective column within the respective bearing.

Additionally or alternatively, wherein the trunnions of the control device may be securely held in the bearings of the frame.

Such an arrangement may provide for a particularly easy assembly process, which allows further assembly to be performed on the frame without risking separation of the control device and the frame.

Additionally or alternatively, the frame may comprise a first arm and a second arm extending substantially in parallel. The first arm may comprise a first bearing of the bearings, and the second arm may comprise a second bearing of the bearings. During arrangement of the trunnions in the bearings, the arms may be configured to flex away from each other to allow arrangement of the trunnions in the bearings, and may be configured to return to a resting position once the trunnions of the control device are arranged in bearings so as to secure the trunnions in the bearings.

Such an arrangement may further ease the assembly of the control device and the frame, as the assembly does not require any tools to secure the trunnions in the bearings. In addition, any misalignment of the control device relative to the shell parts that might be introduced by the flexibility of the arms may advantageously be mitigated by the retainment of the trunnions by the columns of the shell parts.

Additionally or alternatively, the frame may comprise guides for the trunnions, preferably guide ramps, that may lead to the bearings, respectively. A distance between entries of the guides may be greater than an axial distance between ends of the trunnions so that the trunnions of the control device can be inserted into the guides transversely, preferably perpendicularly, to the pivot axis.

Additionally or alternatively, the shell parts may comprise one or more alignment pairs that each may include a first alignment part of one of the shell parts and a corresponding second alignment part of another of the shell parts. The one or more of alignment pairs may be engaged so as to centre or align the columns with respect to each other. In other words, the alignment pairs may urge the column axes towards coinciding.

By providing the endoscope handle with such alignment pairs, any misalignment of column axes may be reduced or even in some cases eliminated.

Additionally or alternatively, the one or more alignment pairs may number three or more.

Additionally or alternatively, the control device may comprise a control lever that may extend radially relative to the pivot axis through a cut-out of the shell parts. The control lever may have an exterior friction-inducing surface for securely engaging with a finger of an operator so as to allow the operator to pivot the control device about the pivot axis.

Additionally or alternatively, the shell parts may comprise a first collar that may surround the first column and may comprise a second collar that may surround the second column. The collars may retain the bearings of the frame.

Additionally or alternatively, the first shell part may comprise the first column, and the second shell part may comprise the second column.

Additionally or alternatively, a separation line between the first shell part and the second shell part may extend in a single plane that may be substantially perpendicular to the column axes.

By providing the endoscope handle in this way, the assembly of the same may be improved, as the shell parts can be joined along the column axes which aids in applying pressure to the trunnions via the columns.

Additionally or alternatively, the frame may comprise one or more first engagement portions that each may interlock with a corresponding second engagement portion of the shell parts.

Additionally or alternatively, the shell parts may comprise one or more snap lock pairs that each may include a male part of one of the shell parts and a corresponding female part of another one of the shell parts. The male snap lock parts may be snap-locked onto the corresponding female snap lock parts to secure the shell parts to each other so as to preferably clamp the trunnions of the control device between the columns of the shell parts, and so as to preferably fix the one or more first engagement portions of the frame within the corresponding second engagement portions of the shell parts, which may thereby fix the frame relative to the shell parts.

Additionally or alternatively, all the male parts may be arranged on one of the shell parts, and all of the female parts may be arranged on the other shell part.

Additionally or alternatively, the one or more snap lock pairs may number at least three, four, five, six, seven, eight, nine or ten.

A second aspect of the invention according to claim <NUM> relates to an endoscope for visually inspecting inaccessible places, the endoscope comprising:.

A third aspect of the invention as defined in claim <NUM> relates to an endoscope system for visually inspecting inaccessible places, such as human body cavities, the endoscope system comprising a monitor and an endoscope comprising endoscope handle according to the first aspect of this disclosure or an endoscope according to the second aspect of this disclosure, wherein the endoscope is connectable to the monitor, and the monitor is configured for displaying an image captured by the vision device of the distal tip part.

A fourth aspect of the invention as defined in claim <NUM> relates to a method of assembling an endoscope handle according to the first aspect of this disclosure, comprising the steps of:.

A person skilled in the art will appreciate that any one or more of the above aspects of this disclosure and embodiments thereof may be combined with any one or more of the other aspects of this disclosure and embodiments thereof.

Embodiments of this disclosure will be described in more detail in the following with regard to the accompanying figures. The figures show one way of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

In the following figure description, the same reference numbers refer to the same elements and may thus not be described in relation to all figures. Further, a prime symbol is suffixed for each ordinal element, i.e. a first element is denoted without a prime symbol, a second element of the same type is denoted with a single prime symbol, and a third element of the same type is denoted with two prime symbols and so on.

<FIG> illustrates an endoscope <NUM>, which is disposable and not intended to be cleaned and reused. The endoscope <NUM> comprises a distal tip part <NUM>, a handle <NUM> for gripping with a control device <NUM>, an insertion tube <NUM> for insertion into a patient, and a bending section <NUM>. The bending section <NUM> comprises articulated segments connected by living hinge members as shown in <FIG> and is typically formed in one piece by injection moulding. The bending section <NUM> is connected between the distal tip part <NUM> and the insertion tube <NUM>. The insertion tube <NUM> extends between the handle <NUM> and the bending section <NUM>. The insertion tube <NUM> has an exterior tubular surface facing the surroundings of the endoscope <NUM>. The distal tip part <NUM> includes an image sensor (not shown) positioned in an interior cavity (not shown) of the distal tip part <NUM>.

In <FIG>, a monitor <NUM> is shown. The monitor <NUM> comprises a cable socket <NUM> to which a monitor cable <NUM> of the endoscope <NUM> (shown in <FIG>) can be connected to establish signal communication between the image sensor of the distal tip part <NUM> and the monitor <NUM>. The monitor <NUM> display images and/or video captured by the image sensor of the endoscope <NUM> thus allowing an operator to "see" the body cavity through the image sensor of the endoscope <NUM>.

Turning to <FIG>, the components of the endoscope <NUM> is shown in greater detail in an exploded view. The endoscope handle <NUM> comprises a first shell part <NUM>, a second shell part <NUM>', a frame <NUM>, and the control device <NUM>. Two steering wires <NUM>, <NUM>' each extend from the control device <NUM> through a respective wire tube <NUM>, <NUM>' running through the insertion tube <NUM> and the bending section <NUM>, wherein the steering wires <NUM>, <NUM>' are connected via a wire loop located between the bending section <NUM> and the distal tip part <NUM>. A working channel extends inside a working channel tube <NUM> that runs along the inside of the insertion tube <NUM> and the bending section <NUM> from fluid openings <NUM>', <NUM>" of a fluid handling device <NUM> to a distal opening (not shown) in the distal tip part <NUM>. The working channel allows liquid or air to be added to and/or removed from the body cavity or allows for insertion of medical tools or surgical instruments into the body cavity.

Turning to <FIG>, the details of the frame <NUM>, the control device <NUM>, and the fluid handling device <NUM> are shown.

As best seen in <FIG>, the frame <NUM> extends along a longitudinal axis L between a proximal longitudinal end <NUM> and a second longitudinal end <NUM>. The frame <NUM> comprises a first bearing <NUM>, as shown in <FIG>, and a second bearing <NUM>', as shown in <FIG>. The frame <NUM> and the bearings <NUM>, <NUM>' are formed in a single piece of a polymer material, preferably by injection moulding.

As best seen in <FIG>, the control device <NUM> is arranged at the proximal longitudinal end <NUM> of the frame and comprises a cylindrical body <NUM> with trunnions <NUM>, <NUM>' (visible in <FIG> and in particular in <FIG>), and a control lever <NUM>. The trunnions <NUM>, <NUM>' extend from opposite sides of the body <NUM> along a pivot axis P. The control lever <NUM> has an exterior friction-inducing surface <NUM> for securely engaging with a finger of an operator so as to allow the operator to pivot the control device <NUM> about the pivot axis P.

As seen in <FIG>, the ends of the two steering wires <NUM>, <NUM>' are guided around respective wire loop portions <NUM>, <NUM>' of the body <NUM> and crimped onto the same steering wire <NUM>, <NUM>' via crimps <NUM>, <NUM>' so as to fix the steering wires <NUM>, <NUM>' to the control device. Since the steering wires run inside wire tubes <NUM>, <NUM>' which are fixed, the control device <NUM> can thus steer the distal tip part <NUM> of the endoscope when an operator manipulates the friction-inducing surface <NUM> of the control lever <NUM> to pivot the control device <NUM> about the pivot axis P and thus tension one of the steering wires <NUM>, <NUM>'. This principle may be known as a Bowden cable.

The steering wires <NUM>, <NUM>', the working channel tube <NUM>, the cable <NUM> run along the inside of the insertion tube <NUM> which terminates at its proximal end in an end cap <NUM>. The end cap <NUM> is arranged about the distal longitudinal end <NUM> of the frame <NUM>.

The frame further comprises a first arm <NUM> having the first bearing <NUM>, and a second arm <NUM>' having the second bearing <NUM>'. The arms <NUM>, <NUM>' extend substantially in parallel. The arms <NUM>, <NUM>' comprises respective ramps <NUM>, <NUM>' oriented along the longitudinal axis L and leading to the bearings <NUM>, <NUM>' as best seen in <FIG>. Further, the arms <NUM>, <NUM>' are configured, when inserting the trunnions <NUM>, <NUM>' in the ramps <NUM>, <NUM>', to flex away from each other to allow insertion of the trunnions <NUM>, <NUM>' in the bearings <NUM>, <NUM>', and to return to a resting position once the trunnions <NUM>, <NUM>' of the control device <NUM> are arranged in bearings <NUM>, <NUM>' so as to securely hold the trunnions <NUM>, <NUM>' in the bearings <NUM>, <NUM>', and accordingly mount the control device <NUM> to the frame <NUM>.

The first shell part <NUM> comprise a first column <NUM>, see <FIG>, <FIG>. The second shell part <NUM>' comprises a second column <NUM>', see <FIG>. Turning specifically to <FIG>, the columns <NUM>, <NUM>' extend along a respective column axis C, C' and into the cavity <NUM> from opposite sides.

The first shell part <NUM> comprises three first alignment parts 64a, 64a', 64a", as best seen in <FIG>, forming three alignment pairs together with three corresponding second alignment parts (not shown) of the second shell part <NUM>'. The alignment pairs are configured, upon closure of the shell parts, to align the column axes C, C' with respect to each other, and thus the alignment pairs are arranged substantially along the separation line <NUM> of the shell parts <NUM>, <NUM>' and circumscribe the body <NUM> of the control device <NUM>, as indicated by the first alignment parts 64a, 64a', 64a" in <FIG>.

The endoscope handle <NUM> further comprises a fluid handling device <NUM> in the form of a T-connector fluid fitting, as best seen in <FIG>, <FIG> and <FIG>, which is formed separately from the frame <NUM>. The fluid handling device is arranged substantially at the distal longitudinal end <NUM> of the frame <NUM>. In other words, the control device <NUM> and the fluid handling device <NUM> are arranged at opposite longitudinal ends of the frame <NUM>. As best seen in <FIG>, the fluid handling device comprises a fluid passage <NUM> having a first fluid opening <NUM> and further a second fluid opening <NUM>', and a third fluid opening <NUM>" as shown in <FIG> and <FIG>. a proximal opening <NUM> of the working channel tube <NUM> is arranged in the first fluid opening <NUM> and is in fluid communication with the second fluid opening <NUM>' and the third fluid opening <NUM>".

The fluid handling device <NUM> is securely mounted onto the frame <NUM> via an interface in the form of a prismatic joint comprising a slot <NUM> and a pin <NUM> secured to the slot <NUM>. In this embodiment, the slot <NUM> forms part of the fluid handling device <NUM> as shown in <FIG> and the pin <NUM> forms part of the frame <NUM> as shown in <FIG> but may in other embodiments be vice versa.

The pin <NUM> comprises a body 78b extending along a pin direction (through the plane of <FIG>) and a head 78a. As best seen in <FIG>, the body 78b is accommodated in the slot <NUM> and terminates in the head 78a, which secures the pin <NUM> to the slot <NUM> by preventing removal of the pin along the pin direction.

The slot <NUM> defines a pre-determined path extending along the longitudinal axis L between a proximal end position 93a of the slot <NUM>, which is closest to the proximal longitudinal end <NUM> of the frame <NUM>, and a distal end position 93b of the slot <NUM>, which is farthest from the proximal longitudinal end <NUM> of the frame <NUM>.

In the arrangement shown in <FIG>, i.e. prior to assembly with the shell parts <NUM>, <NUM>', the interface permits translational movement of the pin <NUM> in the slot <NUM> between the proximal end position 93a of the slot <NUM> and the distal end position 93b of the slot <NUM>. The distance between the proximal end position 93a and the distal end position 93b is in the range of <NUM> to <NUM>, preferably around <NUM>, as this has been found to allow movement to absorb typical dimensional variation. However, the distance may be even less or more in some embodiments. Further, the working channel tube <NUM> is arranged with enough slack to allow movement of the fluid handling device <NUM> relative to the frame <NUM> via the interface.

As best seen in <FIG>, <FIG>, the frame <NUM> comprises a first tube guide passage <NUM> accommodating the working channel tube <NUM> and guiding the tube <NUM> towards the second longitudinal end <NUM> of the frame <NUM> (see <FIG>) and towards the first fluid opening <NUM> (see <FIG>). The fluid handling device <NUM> comprises a second tube guide passage <NUM> that accommodates the tube <NUM> and guides the tube <NUM> from the first fluid opening <NUM> and towards the first tube guide passage <NUM>. The first tube guide passage <NUM> and the second tube guide passage <NUM> are separated by a gap <NUM>, as best seen in <FIG>. The tube guide passages <NUM>, <NUM> are formed as open channels having a channel bottom and two opposing channel walls and an open top side providing access to the channel. This allows the assembler to fit the tube <NUM> within the tube guide passages <NUM>, <NUM> through the open top side.

The frame comprises two first engagement portions <NUM>, <NUM>' interlocking with two corresponding second engagement portions <NUM>, <NUM>' of the shell parts <NUM>, <NUM>', as best seen in <FIG>. The bearings <NUM>, <NUM>' also function as two further first engagement portions, and the collars <NUM>, <NUM>' also function as two further corresponding second engagement portions. The corresponding first and second engagement portions are configured, upon closure of the shell parts <NUM>, <NUM>', to engage and fix the frame <NUM> within the shell parts <NUM>, <NUM>'.

The shell parts <NUM>, <NUM>' comprise nine snap lock pairs. Each pair includes a male part 65a of one of the shell parts <NUM>, <NUM>' and a corresponding female part 65b of another one of the shell parts <NUM>, <NUM>'. The snap lock pairs are configured to be engaged upon closure of the shell parts <NUM>, <NUM>' to fix the shell parts to each other.

The endoscope handle <NUM> can be assembled as follows. The frame <NUM> including the mounted control device <NUM>, fluid handling device <NUM>, and end cap <NUM> is arranged in one of the shell parts <NUM>, <NUM>' and the other shell part is placed over to close the shell parts <NUM>, <NUM>'.

During the closure, the columns <NUM>, <NUM>' are arranged in the bearings <NUM>, <NUM>' of the frame <NUM> abutting the trunnions <NUM>, <NUM>' while allowing the control device <NUM> to pivot around the pivot axis P. The bearings <NUM>, <NUM>' of the frame <NUM> are arranged in collars <NUM>, <NUM>' so that the collars <NUM>, <NUM>' retain the bearings <NUM>, <NUM>'.

Furthermore, the alignment pairs are engaged so as to align the columns <NUM>, <NUM>' with respect to each other. In other words, the column axes C, C' are aligned towards coinciding. The corresponding first and second engagement portions engage and fix the frame <NUM> within the shell parts <NUM>, <NUM>'. A flange <NUM> of the fluid handling device <NUM> is arranged in a slit <NUM> of the first shell part <NUM>', which fixes the fluid handling device <NUM> relative to the frame <NUM> (which are fixed via the engagement portions) so that the fluid handling device <NUM> is locked in a position within the pre-determined path in the range from the proximal end position 93a to the distal end position 93b. Accordingly, the fluid handling device <NUM> is adjusted to absorb tolerances of the frame <NUM> and shell parts <NUM>, <NUM>'.

Lastly, the male snap lock parts 65a are snap-locked onto the corresponding female snap lock parts 65b to secure the shell parts <NUM>, <NUM>' to each other so as to clamp the trunnions <NUM>, <NUM>' of the control device <NUM> between the columns <NUM>, <NUM>' of the shell parts <NUM>, <NUM>'. Accordingly, the trunnions <NUM>, <NUM>' are retained between the columns <NUM>, <NUM>'. Since the clamping force experienced by the trunnions <NUM>, <NUM>' substantially coincides with the pivot axis P, as seen in <FIG>, the pivoting of the control device about the pivot axis P is largely unaffected. The trunnions <NUM>, <NUM>' and the columns <NUM>, <NUM>' are supported by the bearings <NUM>, <NUM>' of the frame <NUM> so that the control device <NUM> is rotatable about the pivot axis P. Each trunnion <NUM>, <NUM>' extends partly through the respective bearing <NUM>, <NUM>' and mates with the respective column <NUM>, <NUM>' within the respective bearing <NUM>, <NUM>'. The first shell part <NUM> comprises a first collar <NUM>, and the second shell part <NUM>' comprises a second collar <NUM>'. The collars <NUM>, <NUM>' each surround the respective column <NUM>, <NUM>' and retains the respective bearings <NUM>, <NUM>' of the frame <NUM>, as best seen in <FIG>.

Once closed, the shell parts <NUM>, <NUM>' form an exterior surface <NUM> shaped to form an ergonomic grip for the operator. The exterior surface <NUM> is divided by a separation line <NUM> (as seen in <FIG>) that extends in a single plane, which is perpendicular to the column axes C, C', as best seen in <FIG>. The separation line <NUM> defines the border between the shell parts <NUM>, <NUM>'. The shell parts <NUM>, <NUM>' enclose a cavity <NUM>, which accommodates the frame <NUM> and the body <NUM> of the control device <NUM>, while the control lever <NUM> extends radially relative to the pivot axis P through a first cut-out 68a of the exterior surface <NUM> of the shell parts <NUM>, <NUM>', as shown in <FIG> and <FIG>.

Claim 1:
An endoscope handle for an endoscope for visually inspecting inaccessible places, such as human body cavities, the endoscope handle comprising:
- a frame (<NUM>) comprising bearings (<NUM>, <NUM>');
- a control device (<NUM>) comprising a body (<NUM>) and trunnions (<NUM>, <NUM>'), the trunnions extending from opposite sides of the body along a pivot axis (P), the control device being configured for steering a distal end (<NUM>) of the endoscope by pivoting about the pivot axis; and
- a first shell part (<NUM>) and a second shell part (<NUM>') together enclosing a cavity (<NUM>) accommodating the frame and at least partly the control device therein, the shell parts forming an exterior surface (<NUM>) shaped to form an ergonomic grip for an operator, and the shell parts comprising a first column (<NUM>) extending along a first column axis (C) and a second column (<NUM>') extending along a second column axis (C'), the first and second columns extend into the cavity from opposite sides,
wherein the trunnions of the control device and preferably the columns are supported by the bearings of the frame so that the control device is rotatable about the pivot axis, characterized in that the shell parts and the frame each are formed as separate components and in that the first and second columns of the shell parts are arranged to retain the trunnions of the control device between the first and second columns of the shell parts.