Liquid guiding structure, coil-less heating element and power management unit for electronic cigarettes (fontem holdings 1 b.v.) electricity in homes

An electronic smoking device, such as an electronic cigarette (e-cigarette), typically has a housing accommodating an electric power source (e.g. a single use or rechargeable battery, electrical plug, or other power source), and an electrically operable atomizer. The atomizer vaporizes or atomizes liquid supplied from a reservoir and provides vaporized or atomized liquid as an aerosol. Control electronics control the activation of the atomizer. In some electronic cigarettes, an airflow sensor is provided within the electronic smoking device which detects a user puffing on the device (e.g., by sensing an under-pressure or an air flow pattern through the device). The airflow sensor indicates or signals the puff to the control electronics to power up the device and generate vapor. In other e-cigarettes, a switch is used to power up the e-cigarette to generate a puff of vapour.

Atomizers in electronic smoking devices may have undesirable characteristics, such as poor atomization, large liquid drops in the final atomized vapor, nonuniform vapor caused by different sizes of liquid drops, too much moisture in the vapor, and/or poor mouthfeel, etc. Accordingly, there is a need for improved atomization in these devices.

In accordance with one aspect of the present invention there is provided an electronic cigarette including a liquid supply, an air inlet, an inhalation port, and an atomizer within a housing. The atomizer includes a heating element which comprises a first lead, a second lead, a plurality of organic or inorganic conductive fibers electrically connected to the first and the second leads, and a first pad and a second pad sandwiching at least a portion of the fibers between the two leads. The electronic cigarette further includes an electric power source within the housing, such as a battery. The first lead and the second lead are electrically connected to the electric power source.

Optionally a gasket is placed between the liquid supply and the first pad such that one surface of the gasket contacts the liquid supply and an opposite surface of the gasket contacts the first pad, thereby conducting the liquid to the first pad, and subsequently to the conductive fibers. The gasket can be made of wood fiber.

In accordance with another aspect of the present invention there is provided an electronic cigarette including a dynamic output power management unit for an electronic cigarette, provides a substantially constant amount of vaporized liquid in a predetermined time interval, for example, the duration of one puff. This can increase compatibility of an electronic cigarette to various types of heating elements, and/or may compensate for dropping output voltage of the power source.

With the present PMU the discharging time of the power source is adjusted dynamically to obtain more consistent vaporization over the same time interval. Consequently a more consistent amount of aerosol may be inhaled by a user during each puff.

To compensate for a dropping output voltage of the power source drops over the discharging time, waveform control technique, for example, PWM (pulse width modulation) technique maybe used to control a at least one switching element within the heating circuit, to control the active time of the heating circuit. A waveform generator can be used to generate the desired control waveform. The waveform generator can be a PWM waveform generator within a PWM controller or PWM module in a microcontroller, for example, a MOSFET. A high-time and low-time ratio is determined, which is then used by the PWM controller for controlling the ON/OFF switching of the heating circuit.

In designs where the resistance of the heating element changes as the working temperature changes, the instantaneous resistance of the heating element may be measured in real-time by incorporating a reference component, for example a reference resister, into the heating circuit to control the active time of the heating circuit.

Changing resistance of the heating element may change the amount of aerosol generated during the process of vaporization, resulting in variation in the amount of the resulting in variations in the amount or character of the vapor generated, the nicotine for example, need to be controlled within a particular range so that human being’s throat will not be irritated or certain administrative regulatory requirements could be meet. Therefore, another benefit of the dynamic output power management technique is that it can be compatible to various types of heating elements, for example, coil-less heating element, such as fiber based heating element, among others. Especially for heating element made from fibers, carbon fiber bundles for example, of which a precise resistance cannot be feasibly maintained for all the carbon fiber bundles in a same batch, the dynamic output management technique is desirable since it can adjust the output power within a range in responsive to carbon fiber bundles with resistance within a range of, for example 1.5 ohms. This would alleviate the burden of the manufacturing process of the carbon fiber bundle and lower the cost of the carbon fiber bundles as a result. The characteristics, features and advantages of this invention and the manner in which they obtained as described above, will become more apparent and be more clearly understood in connection with the following description of exemplary embodiments, which are explained with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 3(a)-3(c) illustrate a coil-less heating element having a liquid guiding structure in contact with a liquid supply. FIG. 3(a) is an enlarged side view of a coil-less heating element without a gasket in contact with a liquid supply. FIG. 3(b) is an enlarged side view of a coil-less atomizer with a gasket in contact with a liquid supply. FIG. 3(c) is a top cross-section view of a coil-less heating element of FIG. 3(a) or FIG. 3(b) in contact with a liquid supply. The gasket is between the liquid supply and the first pad of the liquid guiding structure and therefore not shown from the top view;