Radio frequency heating system and aerosol generating equipment

Abstract

The invention provides a radio frequency heating system and aerosol generating equipment. The system comprises a radio frequency source, a power divider, a phase shifter and a radio frequency radiator which are sequentially coupled, a high-power electromagnetic wave signal is generated through the radio frequency source, and then the high-power electromagnetic wave signal is sequentially processed by the power divider and the phase shifter to obtain multiple paths of radio frequency band electromagnetic wave signals with different phases; therefore, the distribution uniformity of an electromagnetic field generated by the radio frequency radiator based on the radio frequency section electromagnetic wave signal is improved, a heated medium in the radio frequency radiator can be fully heated to improve the continuity of aerosol, meanwhile, the power at the input position of the electromagnetic wave signal can be prevented from being too large, and the service life and the safety of equipment are effectively improved.

Description

Technical Field

[0001] The present application relates to the field of radio frequency heating technology, and in particular to a radio frequency heating system and an aerosol generating device. Background Art

[0002] Among the current aerosol generating devices, aerosols are usually generated based on resistive, ultrasonic, infrared, electromagnetic, and radio frequency principles. Among them, a radio frequency aerosol generating device is a device whose resonant cavity structure is mainly a radio frequency radiator structure. The resonant cavity structure of a radio frequency aerosol generating device usually has a pin-type and a non-pin-type structure. The pin-type structure causes the bulk electric field distribution of the heated medium to be concentrated in the central area of ​​the heated medium, causing the temperature in the central area to be concentrated. There are disadvantages such as uneven aerosol generation, easy burning of the heated medium, and residues of the heated medium at the pins. The non-pin-type structure has single-port and dual-port feeding modes. Compared with the pin-type structure, the main disadvantages are that the power of the fed radio frequency signal is too large, and the electric field concentration is easy to generate at the signal access point, resulting in a reduced service life of the equipment. At the same time, the single-port and dual-port structures also lead to uneven electric field distribution, resulting in poor continuity of the generated aerosol and low utilization of the heated medium. Summary of the Invention

[0003] The main purpose of this application is to provide a radio frequency heating system and an aerosol generating device, which can at least solve the problems of poor continuity and uniformity of the aerosol generated by the relevant aerosol generating device, and low energy utilization rate of the equipment and utilization rate of the heated medium.

[0004] To achieve the above-mentioned objectives, the first aspect of the present application provides a radio frequency heating system, which includes: a radio frequency source, a power divider, a phase shifter and a radio frequency radiator coupled in sequence, wherein: the radio frequency source is used to receive a DC signal transmitted from an external source and convert the DC signal into a first electromagnetic wave signal; the power divider is used to distribute power on the first electromagnetic wave signal output by the radio frequency source to obtain multiple second electromagnetic wave signals of the same phase; the phase shifter is used to phase shift the multiple second electromagnetic wave signals output by the power divider to obtain multiple third electromagnetic wave signals of different phases; the radio frequency radiator is used to generate a corresponding electromagnetic field based on the multiple third electromagnetic wave signals transmitted by the phase shifter; wherein the electromagnetic field is used to heat the heated medium in the radio frequency radiator to generate an aerosol.

[0005] Furthermore, the radio frequency radiator includes an outer conductor device and an inner conductor device coupled to each other; the outer conductor device is used to transmit the plurality of third electromagnetic wave signals to the inner conductor device, so as to generate a corresponding electromagnetic field in the heated medium in combination with the inner conductor device.

[0006] Furthermore, the radio frequency radiator also includes a plurality of radio frequency transmission connectors; the radio frequency transmission connectors are used to transmit the plurality of third electromagnetic wave signals to the outer conductor device and provide a stable input impedance.

[0007] Furthermore, the radio frequency radiator further includes a reference potential component, the reference potential component is coupled to the outer conductor component, and the reference potential component is used to limit the distribution range of the electromagnetic field.

[0008] The second aspect of the present application provides an aerosol generating device, comprising the radio frequency heating system provided in the first aspect of the present application.

[0009] As can be seen from the above, the RF heating system and aerosol generating equipment provided by the present application scheme generate high-power electromagnetic wave signals through a RF source, and then obtain multiple RF electromagnetic wave signals with different phases through processing by a power divider and a phase shifter, thereby ensuring that the multiple RF electromagnetic wave signals generate a uniformly distributed electromagnetic field in the RF radiator, so that the heated medium can be fully heated to improve the continuity of the aerosol, while avoiding excessive power at the input of the electromagnetic wave signal, thereby improving the service life and safety of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 A schematic structural diagram of a first radio frequency heating system provided in an embodiment of the present application; Figure 2 A schematic structural diagram of a second radio frequency heating system provided in an embodiment of the present application; Figure 3 A schematic structural diagram of a radio frequency radiator provided in an embodiment of the present application; Figure 4 A schematic structural diagram of a third radio frequency heating system provided in an embodiment of the present application; Figure 5 This is a schematic structural diagram of the fourth radio frequency heating system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0012] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0013] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, the meaning of "plurality" is two or more, unless otherwise clearly specified.

[0014] In order to solve the problems of poor continuity of aerosols generated by related aerosol generating devices and low utilization rate of heated media, the present application provides a radio frequency heating system, such as Figure 1 For the structural diagram of the first radio frequency heating system provided in this embodiment, please refer to Figure 1 The RF heating system includes a RF source 100, a power divider 200, a phase shifter 300 and a RF radiator 400 coupled in sequence, wherein: the RF source 100 is used to receive a DC signal transmitted from an external source and convert the DC signal into a first electromagnetic wave signal; the power divider 200 is used to distribute power of the first electromagnetic wave signal output by the RF source 100 to obtain multiple second electromagnetic wave signals with the same phase; the phase shifter 300 is used to phase shift the multiple second electromagnetic wave signals output by the power divider 200 to obtain multiple third electromagnetic wave signals with different phases; the RF radiator 400 is used to generate a corresponding electromagnetic field based on the multiple third electromagnetic wave signals transmitted by the phase shifter 300; wherein the electromagnetic field is used to heat the heated medium 410 in the RF radiator 400 to generate an aerosol.

[0015] It should be understood that radio frequency (RF) is a high-frequency, alternating electromagnetic wave. The basic principle of RF heating is to use the energy of a high-frequency electromagnetic field to stimulate molecular motion within an object, thereby generating heat. High-frequency electromagnetic fields typically range from 10kHz to 100MHz. These waves can penetrate the surface of an object and directly act on its interior. When the molecules within the object are affected by the high-frequency electromagnetic field, friction and collisions occur, generating heat. This heat generation is very rapid, typically within a few seconds.

[0016] Since the radio frequency heating system based on the related art may have the problem of electric field concentration at the input of the radio frequency signal (i.e., electromagnetic wave signal) and excessive radio frequency signal, which leads to the disadvantage of shortening the service life of the equipment, this embodiment uses a power divider 200 and a phase shifter 300 to process the radio frequency signal, so that the radio frequency signal can be input to the radio frequency radiator at different phases to adjust the power of the output electromagnetic wave signal, thereby avoiding the problem of electric field concentration at the input of the radio frequency signal, effectively improving the uniformity of the electric field distribution and the utilization rate of energy and materials. Specifically, in this embodiment, the electromagnetic wave signal is generated by the radio frequency source 100, and the radio frequency source 100 can convert the external input DC signal into the electromagnetic wave signal. The DC signal can be provided by an external power supply, which can be connected to the mains through a power interface or provided by a battery. The DC source voltage of the power supply can be 4 to 6V. If a solid-state power supply is used, the battery capacity can be 2000 to 4000mAH. When the mains is used as the power supply, an AC / DC converter can be added accordingly for voltage conversion. After the power supply outputs the DC signal to the RF source 100, the RF source 100 will generate a stable high-power electromagnetic wave signal in the RF band, and then through the action of the power divider 200 and the phase shifter 300, the high-power electromagnetic wave signal is processed into multiple electromagnetic wave signals with different phases.

[0017] It can be understood that the power divider 200, also known as a power divider, can divide one input signal into two or more signals with equal or unequal energy. The selection of an equal-divided power divider 200 or an unequal-divided power divider 200 can be determined according to the electric field distribution requirements or the temperature field distribution requirements of the heated medium. The power divider 200 in this embodiment is used to distribute the high-power RF band electromagnetic wave signal output by the RF source into RF band electromagnetic wave signals of the same phase and frequency with the same power or different power, and then output these RF band electromagnetic wave signals to the phase shifter 300. The phase shifter 300 will then phase-shift the RF band electromagnetic wave signals of different channels, thereby obtaining multiple RF band electromagnetic wave signals with different phases. The phase shifter 300 in this embodiment can also be selected from a switch phase shifter, a load phase shifter, a hybrid phase shifter, a high-pass and low-pass phase shifter, etc. according to the electric field distribution requirements or the temperature field distribution requirements of the heated medium.

[0018] The RF radiator 400 in this embodiment serves as a container for the heated medium and a radiating element for generating an electromagnetic field. Upon receiving an RF electromagnetic wave signal, the RF radiator 400 generates a high-frequency electromagnetic field based on the RF electromagnetic wave signal. Based on the principle of dielectric heating, the heated medium generates heat and forms an aerosol within a very short time, such as 0.5 to 5 seconds. The uniformly distributed high-frequency electromagnetic field effectively improves the utilization rate of the heated medium and maintains uniformity and connectivity in the aerosol generated by the heated medium. The heated medium in this embodiment replaces the combined heating element and heated element in traditional aerosol-generating devices. Depending on actual needs and taking into account the dielectric properties of the heated medium (i.e., relative permittivity and loss tangent) and the basic principles of dielectric heating, a solid aerosol-generating medium containing polar molecules, such as heat-not-burn (HNB), or a liquid aerosol-generating medium containing polar molecules, such as e-liquid, can be selected to meet the needs of different products.

[0019] like Figure 2 The figure shows the structure of the second radio frequency heating system provided in this embodiment. Figure 2 The radio frequency radiator 400 includes an outer conductor component 420 and an inner conductor component 430 coupled to each other; the outer conductor component 420 is used to transmit multiple third electromagnetic wave signals to the inner conductor component 430, so as to generate a corresponding electromagnetic field in the heated medium 410 in combination with the inner conductor component 430.

[0020] Specifically, in this embodiment, the RF radiator 400 includes two conductors that cooperate with the input RF electromagnetic wave signal to generate a corresponding high-frequency electromagnetic field. The two conductors are arranged in parallel, with one of them being closer to the phase shifter 300 being the outer conductor 420 and the other being closer to the heated medium 410 being the inner conductor 430. The two conductors may have a cage-like structure. The two conductors can be combined to provide different operating frequencies corresponding to dynamic optimal power, which can be adjusted by changing the size of the resonant ring of the inner conductor. Furthermore, the operating frequency corresponding to dynamic optimal power can be determined based on the amount of heated medium and the size of the radiator. For example, the operating frequency corresponding to dynamic optimal power ranges from 0.5 to 10 GHz for the radiator size and amount of heated medium used in common aerosol generating devices. Furthermore, a dielectric layer, such as a cage-like structure, may be provided between the inner and outer conductors 430 and 420 to separate the two conductors. The inner and outer conductors 430 can be made of high-conductivity materials such as copper, aluminum, silver, and gold, with a thickness ranging from 0.035 to 0.105 mm. The dielectric layer can be made of common high-frequency PCB substrate materials, such as FR4 and Rogers 4350B. The dielectric constant and loss tangent are selected based on the electric field constraint and coupling effect. The dielectric layer thickness can be between 0.78 and 2.36 mm.

[0021] Furthermore, in some implementations of this embodiment, the RF radiator 400 further includes a plurality of RF transmission connectors 440 ; the RF transmission connectors 440 are configured to transmit a plurality of third electromagnetic wave signals to the outer conductor component 420 and provide a stable input impedance.

[0022] Furthermore, in some implementations of this embodiment, the radio frequency radiator 400 further includes a reference potential component 450 . The reference potential component 450 is coupled to the outer conductor component 420 . The reference potential component 450 is used to limit the distribution range of the electromagnetic field.

[0023] Specifically, in this embodiment, in order to avoid the problem of excessive power at the connection caused by the RF radiator 400 using a single port to receive the RF signal, the RF radiator in this embodiment is set to a multi-port structure, and multiple RF transmission connectors 440 are used to receive multiple RF signals with different initial phases output by the phase shifter 300, and input the RF signal to the cage-shaped outer conductor device 420, while providing a stable access impedance for the RF radiator 400; and to ensure that the power in the RF radiator 400 is in a balanced state after the RF signal is input, the number of RF transmission connectors 440 should be selected as a number corresponding to the Nth power of 2, such as 2, 4, 8, etc. At the same time, using a number corresponding to the Nth power of 2 also facilitates the front power divider 200 to measure the isolation between the input and output of the RF signal. In addition, the RF radiator 400 in this embodiment is further provided with a reference potential component, and the reference potential portion is respectively connected to the RF transmission connector 440 and the external conductor device 420. The reference potential portion is a reference ground plane, which can be used to constrain the electric field distribution in the heated medium and provide the required reference zero potential position for the RF transmission connector 440. The RF transmission connector 440 in this embodiment can optionally adopt an SMA connector. The SMA connector can select different feeding positions according to the electromagnetic field distribution requirements and the working conditions of the phase shifter 300, for example Figure 3 As shown in the structural schematic diagram of the RF radiator (wherein the mark 1 represents the RF transmission connector, 211 represents the inner conductor component, 212 represents the outer conductor component, and 213 represents the dielectric layer), four SMA connectors are respectively arranged on the upper and lower sides of the outer side wall of the cage-shaped outer conductor component 420; the SMA connector can be selected from different types of SMA connectors such as straight pins, offset pins, and elbows according to the structure and position of the outer conductor component 420.

[0024] like Figure 4 The third radio frequency heating system provided in the embodiment of the present application is shown in FIG. Figure 4 The RF heating system also includes a wavelength detector 500 and a control unit 600; the wavelength detector 500 is used to detect the wavelength information of the second electromagnetic wave signal transmitted by the power divider 200; the control unit 600 is used to generate a corresponding phase adjustment control instruction based on the wavelength information of the second electromagnetic wave signal fed back by the wavelength detector 500, and transmit it to the phase shifter 300.

[0025] In some implementations of this embodiment, the control unit 600 is specifically used to: determine a reference phase offset value based on the wavelength information of the second electromagnetic wave signal fed back by the wavelength detector 500 and the length of the preset signal transmission line, and generate a corresponding frequency adjustment control instruction based on the reference phase offset value.

[0026] Specifically, in this embodiment, the control unit 600 generally includes a microcontroller (MCU), which is mainly used to control the RF source 100, the power divider 200, the phase shifter 300, and the RF radiator 400. For example, when controlling the phase shifter 300 to adjust the phase of the RF electromagnetic wave signal, the control unit 600 will sample and amplify the wavelength information of the RF electromagnetic wave signal detected by the wavelength detector 500, and then convert it into a digital signal corresponding to the wavelength information of the RF electromagnetic wave signal through analog-to-digital AD conversion. After that, the control unit 600 calculates a reference phase offset value based on the digital signal and the pre-calibrated line length of the signal transmission line. After obtaining the reference phase offset value, it can also generate corresponding phase adjustment instructions based on the requirements of the uniformity of the electric field distribution to control the phase shifter to perform a corresponding phase offset on the RF electromagnetic wave signal to ensure that the phase offset angle is between 1 and 180°.

[0027] like Figure 5 The fourth radio frequency heating system provided in the embodiment of the present application is shown in FIG. Figure 5 In some implementations of this embodiment, the RF heating system further includes an attenuator 700 for adjusting the power of the first electromagnetic wave signal output by the RF source 100 .

[0028] Furthermore, in some implementations of this embodiment, the RF heating system also includes a power detection unit 800, which includes an output coupler 810; the output coupler 810 is used to detect the power value of the third electromagnetic wave signal output by the phase shifter 300, generate a corresponding power detection signal, and transmit each power detection signal to the control unit 600; the control unit 600 is used to analyze the power detection signal, and compare the power value obtained by analysis with a preset power range value, generate a corresponding power adjustment control instruction based on the comparison result, and transmit it to the attenuator 700.

[0029] Further, see Figure 5 In some implementations of this embodiment, the power detection unit 800 further includes a signal detector 820 , which is configured to feed back the power detection signal output by the output coupler 810 to the control unit 600 .

[0030] Specifically, the power range of the total output power signal of the RF source 100 in this embodiment is approximately 15 to 40 W. In order to ensure that the effective power of the electromagnetic wave signal input to the RF radiator 400 is maintained in a certain range, such as between 1 and 10 W, in addition to setting the power divider 200 as a device that can perform 2N-power power division such as 2-way, 4-way, 8-way, etc., the power of the electromagnetic wave signal input to the power divider 200 can also be adjusted by the control unit 600. Specifically, the power information of the RF electromagnetic wave signal output by the phase shifter 300 can be detected by the output coupler 810, and a corresponding power detection signal carrying power information can be generated. The signal detector 820 then transmits the power detection signal to the control unit 600. The control unit 600 analyzes the power detection signal, samples and amplifies it, and then converts it into a digital signal corresponding to the power detection signal through analog-to-digital AD conversion. Then the control unit 600 matches the digital signal with a pre-calibrated power range value; when the match is unsuccessful, the current RF electromagnetic wave signal is determined. The power of the electromagnetic wave signal does not meet the preset index, and the power of the electromagnetic wave signal needs to be adjusted. The difference between the digital signal corresponding to the power detection signal and the upper limit and lower limit of the power threshold range can be calculated respectively. By comparing the two differences, the smaller difference is determined, and a corresponding power adjustment control instruction is generated based on the smaller difference and output to the attenuator 700, thereby controlling the attenuator 700 to increase or decrease the power of the electromagnetic wave signal. When the digital signal corresponding to the power detection signal matches the pre-calibrated power range value, a control instruction is generated to control the attenuator 700 not to change the output power value of the electromagnetic wave signal. By adjusting the power of the electromagnetic wave signal input to the RF radiator 400 to be within the preset power range, it can also reduce the heat generation and electromagnetic interference of components such as the power divider 200 and the phase shifter 300 during the electromagnetic wave signal transmission process, and at the same time, it can reduce the heat generation at the contact of the RF transmission connector 440.

[0031] Based on the technical solution of the embodiment of the present application, the radio frequency source receives an externally transmitted DC signal and converts the DC signal into a first electromagnetic wave signal; the power divider distributes power on the first electromagnetic wave signal output by the radio frequency source to obtain multiple second electromagnetic wave signals of the same phase; the phase shifter shifts the phase of the multiple second electromagnetic wave signals output by the power divider to obtain multiple third electromagnetic wave signals of different phases; the radio frequency radiator generates a corresponding electromagnetic field based on the multiple third electromagnetic wave signals transmitted by the phase shifter; wherein the electromagnetic field is used to heat the heated medium in the radio frequency radiator to generate aerosol. Through the implementation of the solution of the present application, a high-power electromagnetic wave signal is generated by the radio frequency source, and then processed by the power divider and the phase shifter to obtain multiple radio frequency electromagnetic wave signals of different phases, thereby ensuring that the multiple radio frequency electromagnetic wave signals generate a uniformly distributed electromagnetic field in the radio frequency radiator, so that the heated medium can be fully heated to improve the continuity of the aerosol, while avoiding excessive power at the input of the electromagnetic wave signal, thereby improving the service life and safety of the equipment.

[0032] The present application also provides an aerosol generating device, which includes the radio frequency heating system described above. The aerosol generating device may be an electronic cigarette or other product.

[0033] It should be noted that the various embodiments in the present application are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0034] It should also be noted that, in the present application, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0035] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments shown herein but is intended to be applied in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A radio frequency heating system, characterized in that: The invention comprises a radio frequency source, a power divider, a phase shifter and a radio frequency radiator coupled in sequence, wherein: The radio frequency source is used to receive a DC signal transmitted from an external source and convert the DC signal into a first electromagnetic wave signal; The power divider is used to divide the power of the first electromagnetic wave signal output by the radio frequency source to obtain a plurality of second electromagnetic wave signals with the same phase; The phase shifter is used to perform phase shift on the multiple second electromagnetic wave signals output by the power divider to obtain multiple third electromagnetic wave signals with different phases; The radio frequency radiator is used to generate a corresponding electromagnetic field based on the multiple third electromagnetic wave signals transmitted by the phase shifter; wherein the electromagnetic field is used to heat the heated medium in the radio frequency radiator to generate aerosol.

2. The radio frequency heating system according to claim 1, characterized in that: The radio frequency radiator includes an outer conductor component and an inner conductor component coupled to each other; The outer conductor component is used to transmit the plurality of third electromagnetic wave signals to the inner conductor component, so as to generate a corresponding electromagnetic field in the heated medium in combination with the inner conductor component.

3. The radio frequency heating system according to claim 2, characterized in that: The radio frequency radiator further includes a plurality of radio frequency transmission connectors; The radio frequency transmission connector is used to transmit the plurality of third electromagnetic wave signals to the outer conductor component and provide a stable input impedance.

4. The radio frequency heating system according to claim 2, characterized in that: The radio frequency radiator further includes a reference potential component coupled to the outer conductor component, and the reference potential component is used to limit the distribution range of the electromagnetic field.

5. The radio frequency heating system according to claim 1, characterized in that: Also included is a wavelength detector and a control unit; The wavelength detector is used to detect wavelength information of the second electromagnetic wave signal transmitted by the power divider; The control unit is configured to generate a corresponding phase adjustment control instruction according to the wavelength information of the second electromagnetic wave signal fed back by the wavelength detector, and transmit the instruction to the phase shifter.

6. The radio frequency heating system according to claim 5, characterized in that: The control unit is specifically configured to determine a reference phase offset value based on the wavelength information of the second electromagnetic wave signal fed back by the wavelength detector and the length of a preset signal transmission line, and generate a corresponding phase adjustment control instruction based on the reference phase offset value.

7. The radio frequency heating system according to claim 5, characterized in that: It also includes an attenuator for adjusting the power of the first electromagnetic wave signal output by the radio frequency source.

8. The radio frequency heating system according to claim 7, characterized in that: Also included is a power detection unit, the power detection unit including an output coupler; The output coupler is configured to detect a power value of the third electromagnetic wave signal output by the phase shifter, generate corresponding power detection signals, and transmit each power detection signal to the control unit; The control unit is used to analyze the power detection signal, compare the power value obtained by the analysis with the preset power range value, generate a corresponding power adjustment control instruction according to the comparison result, and transmit it to the attenuator.

9. The radio frequency heating system according to claim 8, characterized in that: The power detection unit further includes a signal detector, which is configured to feed back the power detection signal output by the output coupler to the control unit.

10. An aerosol generating device, characterized in that The method comprises the radio frequency heating system according to any one of claims 1 to 9.

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