Patent Description:
Document <CIT> discloses an ink cartridge for an image forming apparatus comprising a deformable ink waste collection bag.

Various features of the present disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate features of the present disclosure, and wherein:.

The invention is related to a liquid waste container, or reservoir, that delimits an opening and comprises a receptacle, a bistable arrangement and an actuator according to claim <NUM>.

The bistable arrangement has a first stable state and a second stable state, and is arranged such that: when the bistable arrangement is in the first stable state, liquid can be received into the receptacle through the opening; and when the bistable arrangement is in the second stable state, liquid is prevented from exiting the receptacle through the opening. The actuator is arranged to engage with the bistable arrangement to cause the bistable arrangement to transition from the first stable state to the second stable state.

In general, a bistable system is any system that comprises at least two stable equilibrium states. The system can be caused to transition between the at least two stable equilibrium states through an application of an external force, while in an absence of any applied forces, the system remains in its current stable equilibrium state. Thus, a "bistable" as used herein includes systems having two states and systems having three, four or more stable states.

Such a bistable system can be implemented in a liquid-tight sealing mechanism in a liquid waste container. For example, the bistable system can be arranged to allow liquid waste to be received within a receptacle of the liquid waste container when in the first stable state, and can be arranged to prevent liquid waste from being received within, or allow liquid waste to exit, through the receptacle when in the second stable state. The bistable system can be caused to transition between the first and second stable states through an application of an external force provided by an actuator. In some examples, the actuator applies a force to the bistable system when a predetermined condition is met, such as when the liquid waste within the receptacle reaches a predetermined level. In other examples, the actuator applies a force to the bistable system in response to input, such as when a button of the liquid waste container is pressed.

The bistable system can be transitioned back to the first stable state through an application of an additional force. For example, the bistable system may be positioned within the liquid waste container so that it is accessible to allow a force to be applied which causes the transition from the second stable state to the first stable state. This means that leakage of liquid waste is reduced when the liquid waste container is tilted, handled and inverted because the bistable system will tend to remain in the second closed position unless an additional force is applied.

<FIG> shows a schematic representation of a cross section of a liquid waste container <NUM> according to a first example. The example liquid waste container <NUM> delimits an opening, or aperture, <NUM> and comprises: a receptacle <NUM>, a spring membrane <NUM>, an internal float <NUM>, and a guiding arrangement <NUM>.

The spring membrane <NUM> has a unitary construction and comprises a closed surface that forms a boundary separating upper and lower sides of the spring membrane <NUM>. As depicted in cross section in <FIG>, the spring membrane <NUM> takes the form of a spherical cap and may be made from any suitable material that is capable of undergoing elastic deformation, such as silicone rubber. In a first stable state, at least a portion of the spring membrane <NUM> curves downwards, towards the base of the receptacle <NUM>. In this state, the spring membrane <NUM> does not form a seal around the opening <NUM>, because there is a space between the spring membrane <NUM> and the opening <NUM>. Liquid waste can therefore be received into, and can exit, the receptacle <NUM> via the opening <NUM> when the spring membrane <NUM> is in the first state.

The internal float <NUM> is arranged to float over liquid waste <NUM> inside the receptacle <NUM> and therefore follows a liquid waste level within the receptacle <NUM> (from now on referred to as the 'liquid level'), as it varies. In this example, the internal float <NUM> is a hollow sphere, but other shapes can also be used.

The guiding arrangement <NUM> constrains the internal float <NUM> to move along a reversible path as the liquid level <NUM> varies. The internal float <NUM> is constrained to move between a first position, located within the receptacle <NUM>, and a second position located in proximity of the bistable arrangement such that the internal float <NUM> engages with the bistable arrangement when at the second position. More specifically, in this example, the guiding arrangement <NUM> is a hollow tube positioned inside the receptacle <NUM>. To allow liquid to enter and leave the guiding arrangement so that the internal float <NUM> tracks the liquid level, the hollow tube has gaps at each end with the receptacle <NUM>, so that both ends of the tube are open. The hollow tube is be attached to an internal side wall of the receptacle by a support member <NUM> to fix its position within the receptacle <NUM>.

In use, as liquid waste enters the receptacle <NUM>, the liquid level <NUM> rises. Consequently, the internal float <NUM> moves with the rising liquid level in a direction defined by the guiding assembly <NUM>. At some point, the liquid level <NUM> will reach the predetermined level at which the internal float <NUM> will begin to engage with the spring membrane <NUM>.

<FIG> shows a detail schematic view of the spring membrane <NUM> of the liquid waste container <NUM> depicted in <FIG> when the internal float <NUM> engages the spring membrane <NUM>. As the internal float <NUM> engages the spring membrane <NUM>, a small upward force is applied to the spring membrane <NUM> by the internal float <NUM>. The spring membrane <NUM> will, as a consequence of the upward force, deform slightly and exert a balancing force on the internal float <NUM>. As the liquid level <NUM> rises, the spring membrane constrains the internal float <NUM> from rising at the same rate as the liquid. An upthrust force exerted by the liquid on the internal float <NUM> increases, and therefore the balancing deflection force exerted by the spring membrane increases. The spring membrane <NUM> has a maximum possible deflection force that it can exert which is dependent on the type of material the spring membrane <NUM> is made from, and its dimensions. When the upthrust force becomes larger than this maximum possible deflection force of the spring membrane <NUM>, the spring membrane <NUM> suddenly flips upwards into a second stable state.

<FIG> is a schematic cross-sectional view of the liquid waste container <NUM> depicted in <FIG>, when the liquid level <NUM> has exceeded the predetermined level, the internal float <NUM> has engaged the spring membrane <NUM>, applied an upward force to the spring membrane <NUM> and caused it to transition to the second stable state. In the second stable state, at least a portion of the spring membrane <NUM> curves away from the base of the receptacle <NUM>. The spring membrane <NUM> has transitioned into the second stable state where it is in contact with the opening <NUM> and forms a seal around an edge of the opening <NUM>. Liquid waste is therefore prevented from being received into, or exiting from, the liquid waste container <NUM> through the opening <NUM> when the spring membrane <NUM> is in the second stable state.

In some examples, the bistable arrangement, or construction, can be transitioned from the second stable state to the first stable state by an application of an external force to the bistable arrangement. This property allows the liquid waste container <NUM> to be emptied of its contents. In the example liquid waste container <NUM> depicted in <FIG> and <FIG>, the spring membrane <NUM> can be transitioned from the second stable state to the first stable state by physically pressing on the spring membrane <NUM> in the direction into the container, thereby causing it to move into the first stable state. Moving the bistable arrangement into the first stable state unseals the opening <NUM> and allows the contents of the liquid waste container <NUM> to be emptied in a controlled manner.

In some examples, when the liquid waste container <NUM> is inverted while the bistable arrangement is in the second stable state, the bistable arrangement remains in the second stable state reducing the risk of leakage. This property can be seen in <FIG> which shows a cross-sectional view of the example liquid waste container <NUM> of <FIG>, inverted. When inverted, the internal float <NUM> follows the liquid level <NUM>, thereby moving away from the spring membrane <NUM>. Although the float no longer acts on the spring membrane <NUM>, a weight of a column of liquid directly above the spring membrane <NUM> pushes against the spring member, actually increasing the seal formed by the spring membrane <NUM> around the opening <NUM> because of the curvature of the membrane in the second state, further reducing the risk of leakage when inverted. This means that the spring membrane <NUM> stays in the second stable state when inverted and the seal is actually increased when the liquid waste container <NUM> is inverted.

When the bistable arrangement is in the first stable state, as depicted in <FIG>, inversion of the liquid waste container <NUM> will cause the bistable arrangement to transition from the first stable state to the second stable state. This closes the opening <NUM> and reduces the risk of accidental leakage by inversion. This can be understood by referring to the inverted orientation of the liquid waste container <NUM> as depicted in <FIG>. After inversion, a weight of a column of liquid directly above the spring membrane <NUM> may provide at least enough force needed to cause a transition of the bistable arrangement from the first stable state to the second stable state, depending on the amount of liquid within the receptacle <NUM>. Therefore, if the liquid waste container <NUM> is removed from the system before the spring membrane <NUM> has transitioned to the second stable state, inverting the liquid waste container <NUM> will cause the spring membrane <NUM> to transition to the first stable state, closing off the opening <NUM> and reducing the risk of leakage.

As discussed above, in an example the guiding arrangement <NUM> is a hollow tube with both ends spaced from the receptacle <NUM>. Other forms of guiding arrangement may be used. In another example the guiding assembly <NUM> extends from a base of the receptacle <NUM> to the second point in proximity with the bistable arrangement. In this case, the hollow tube may comprise openings in its sides such that liquid may flow into and out of the hollow tube. In other examples, the guiding arrangement <NUM> may comprise at least three rod-like members arranged to surround the internal float <NUM> such that the rod-like members act as a track for the internal float <NUM> to travel along as the liquid level <NUM> varies. In any case, the guiding arrangement <NUM> is arranged such that, at hydrostatic equilibrium within the receptacle <NUM>, the liquid waste level inside the guiding arrangement <NUM> is equal to the liquid waste level outside the guiding arrangement <NUM>. This allows the internal float <NUM> to move with the liquid level <NUM>.

<FIG> is a cross-sectional view of a liquid waste container <NUM> according to a second example. The liquid waste container <NUM> has a similar arrangement as the example liquid waste container <NUM> depicted in <FIG>. In the example of <FIG>, the actuator comprises an internal float <NUM> attached to a first end of an elongate member <NUM>. A second end of the elongate member <NUM> is attached to an internal wall of the receptacle <NUM> via a hinge. This allows the elongate member <NUM> to pivot within the receptacle <NUM>, thereby constraining the internal float <NUM> to move along an arc <NUM>.

The operation of the actuator in this example is similar to the operation of the internal float <NUM> and guiding arrangement <NUM> of the liquid waste container <NUM>. Initially, the liquid level <NUM> may be below the predetermined level. As liquid waste is added to the receptacle <NUM> through an opening <NUM>, the liquid level <NUM> rises. Due to buoyancy, the internal float <NUM> moves with the rising liquid level <NUM>. The internal float <NUM> thereby traces out the arc <NUM> defined by the elongate member <NUM> as it pivots within the receptacle <NUM>. When the liquid level <NUM> reaches the predetermined level, the internal float <NUM> engages with a spring membrane <NUM>, causing it to transition from the first stable state to the second stable state in a similar manner as explained above with reference to <FIG>.

<FIG> is a cross-sectional view of a liquid waste container <NUM> according to another example. The liquid waste container <NUM> is the same as the liquid waste container <NUM>, but the opening <NUM> of the liquid waste container <NUM> is positioned within the receptacle <NUM> and connected to a surface of the liquid waste container <NUM> via a channel <NUM>. This is useful for when liquid waste continues to be dispensed towards the opening <NUM> after the liquid waste container <NUM> is sealed by the operation of the actuator. For example, it may not be possible to stop the flow of liquid waste immediately when the actuator causes the spring membrane <NUM> to transition to the second state. In this case, any additional liquid waste that is dispensed towards the opening <NUM> will collect in the channel <NUM> of the liquid waste container <NUM>. This reduces additional mess that may result from the deposition of additional liquid waste once the liquid level <NUM> has reached the predetermined level and the liquid waste container <NUM> is sealed.

The example liquid waste containers <NUM>, <NUM>, <NUM> above comprise an automatic sealing mechanism that does not need intervention from a user. Once the liquid level <NUM>, <NUM>, <NUM> reaches a predetermined level, the bistable arrangement transitions to a second stable state, thus sealing the liquid waste container <NUM>, <NUM>, <NUM>. However, in some cases, it may be useful to provide a sealing mechanism that is manually operated so that sealing of the liquid waste container <NUM>, <NUM> may be controlled. That is, the transition of the bistable arrangement from the first stable state to the second stable state may be manually operated. This is of use when the liquid waste container is removed from the system before the liquid reaches a predetermined level, such as when a regular maintenance process is carried out to remove, empty and/or replace the liquid waste container.

<FIG> is a cross-sectional view of a further example of a liquid waste container <NUM>. In the example of <FIG>, the actuator comprises a button <NUM> which, when pressed, causes a spring membrane <NUM> to transition from a first stable state to a second stable state.

The button <NUM> acts on a first end of a lever <NUM>. A second end of the lever is positioned near the bistable arrangement and the fulcrum of the lever <NUM> is positioned at a point between the first and second ends and attached to, and spaced from, an upper internal wall of the receptacle <NUM> via an elongate member. When the button is pressed, the first end of the lever <NUM> is pushed downwards into the receptacle <NUM>, pivoting the second end of the lever upwards, towards the opening <NUM>.

When the button <NUM> is pushed down by a predetermined distance, the second end of lever <NUM> is arranged to engage with the spring membrane <NUM>. As the button <NUM> is further pressed down, the second end of the lever <NUM> is further pressed into the spring membrane <NUM>. At some point, the leverage force provided by pressing the button <NUM> overcomes the maximum balancing deflection force of the spring membrane <NUM> causing it to transition from the first stable state to the second stable state. The fulcrum can be positioned closer to the second end of the lever <NUM> than the first end so that the force needed to be applied to the button <NUM> to cause the transition can be adjusted. For example, a relatively high force can be useful to avoid accidental closure, while a relatively low force can be useful to make it easier to close the opening <NUM>. Other examples of button activated mechanisms are possible.

Further implementations are possible. For example, any of the button mechanisms of <FIG> may be implemented alongside the internal float examples depicted in <FIG> so that the transition to the second state is both automatic and manual.

Although the example liquid waste containers <NUM>, <NUM>, <NUM>, <NUM> described above comprise specific examples of bistable arrangements and actuators, alternatives of each are possible. For example, the bistable arrangement, or construction, may comprise any arrangement comprising two stable states. Examples of such bistable arrangements include center-offset springs and cam mechanisms.

Also, the actuator may differ from the example implementations described above. The actuator can be any arrangement that engages with the bistable arrangement to cause it to transition from the first stable state to the second stable state. The type of actuator implemented may depend on the specific bistable arrangement used. In some examples, the actuator may cause the bistable arrangement to transition to the second stable state when the liquid level <NUM>, <NUM>, <NUM> reaches a predetermined level. Alternatively, the actuator may comprise any mechanism that causes the bistable arrangement to transition to the second stable state when a button is pressed.

The above described liquid waste containers can be used in various domestic, commercial and industrial systems that output liquid waste that needs to be captured and stored. An example is a printing device wherein waste print fluid is not applied to a printing substrate and so needs to be captured and contained.

<FIG> shows a schematic diagram of a printing system <NUM> according to an example. Certain examples of liquid reservoirs described herein are implemented within the context of this printing system. The printing system <NUM> may be a 2D printer such as an inkjet or digital offset printer. In the example of <FIG>, the printing system <NUM> comprises a printing device <NUM>, a memory <NUM> and a processor <NUM>. The processor <NUM> may implement machine readable instructions and/or be suitably programmed or arranged hardware.

The printing device <NUM> comprises a source of print fluid <NUM>, and is arranged to apply print fluid to a print target in a printing process, to produce a print output <NUM>. The print output <NUM> may, for example, comprise print fluid deposited on a substrate. The printing device <NUM> may comprise an inkjet deposit mechanism which may, for example, comprise a nozzle to deposit the print fluid. The inkjet deposit mechanism may include circuitry to receive instructions associated with depositing print fluid. The printing device <NUM> may comprise a multi-level drop-weight print device. A multi-level drop-weight printing device is a printing device that is arranged to deposit print fluids with more than one possible drop-weight. The substrate may be paper, fabric, plastic or any other suitable print medium.

In some examples, a process may comprise a printing device maintenance procedure. This may be to assess the performance of a particular component of the printing device <NUM>, to analyze the efficiency of the printing device <NUM> to a particular printing process, or to improve the quality of printing such as by cleaning print heads. The automatic maintenance procedure may involve wiping, spitting or purging of print fluid. In such cases, print fluid from the source of print fluid <NUM> may be deposited by the nozzle, but not applied to a substrate because such procedures are generally carried out without a substrate in place. To prevent damage to the printing device <NUM> or leakage from the printing device <NUM> occurring, the print fluid may be captured and contained in a liquid reservoir <NUM> delimiting an aperture for receiving the print fluid into the reservoir, and which is positioned underneath a print head nozzle.

The printing device <NUM> also comprises a bistable construction and an actuator. The bistable construction is movable between a first stable state and a second stable state, and positioned such that in the first stable state the aperture of the liquid reservoir <NUM> is open, and in the second stable state the aperture is closed. The actuator is arranged to engage the bistable construction and cause the bistable construction to move from the first stable state to the second stable state as described above with reference to the examples shown in <FIG>.

In some cases, the liquid reservoir <NUM> is reusable so that the liquid reservoir <NUM> is removed from the printing device <NUM>, emptied of its contents, and reinserted back into the printing device <NUM> for further use. In other cases, the liquid reservoir <NUM> may be disposable.

The above described liquid reservoir <NUM>-<NUM> provides an effective apparatus for capturing and containing waste print fluid output from a printing device during maintenance procedures. The liquid reservoir has reduced leakage while the bistable construction is in the second state. In some examples, when the liquid reservoir is inverted, the seal formed by the bistable construction is increased by the downward force of the weight of the liquid within the liquid reservoir. In some examples, when the liquid reservoir is removed from the printing device while the bistable construction is in a first stable state, an inversion of the liquid reservoir will provide the force needed to cause the bistable construction to transition to the second stable state and thereby seal the liquid reservoir, further reducing leakage.

Claim 1:
A liquid waste container (<NUM>) delimiting an opening for receiving liquid waste through the opening (<NUM>) into a receptacle (<NUM>) and comprising:
a bistable arrangement (<NUM>, <NUM>) having a first stable state and a second stable state, wherein:
when the bistable arrangement is in the first stable state, liquid can enter the receptacle through the opening; and
when the bistable arrangement is in the second stable state, liquid is prevented from entering the receptacle through the opening; and
an actuator (<NUM>, <NUM>, <NUM>, <NUM>) to engage the bistable arrangement and to cause the bistable arrangement to transition from the first stable state to the second stable state by the application of a force and wherein in the absence of said force the bistable arrangement remains in the second stable state;
wherein the actuator comprises an internal float (<NUM>) constrained to travel along a pre-defined path within the receptacle, and is arranged to cause the bistable arrangement (<NUM>) to transition from the first stable state to the second stable state when a liquid level inside the receptacle reaches a predetermined level.