High-frequency processing equipment

Abstract

A high-frequency processing device according to the present disclosure is equipped with a high-frequency power supply, a high-frequency power radiation unit, an impedance adjustment unit, a power detection unit, and a control unit. The high-frequency power supply generates high frequency power of a variable size. The high-frequency power radiation unit radiates a target object with high-frequency power. The impedance adjustment unit adjusts the load impedance. The power detection unit detects the supplied power and the reflected power. The control unit obtains the load impedance by calculating the reflectance and the phase difference. The control unit determines whether or not the load impedance falls within a prescribed impedance region which corresponds to the output power of the high-frequency power supply. The control unit causes the impedance adjustment unit to guide the load impedance to within the prescribed impedance region which corresponds to the output power of the high-frequency power supply, and to keep the same within said region.

Description

[Technical Field]

[0001] The present disclosure relates to a high-frequency processing apparatus for processing an object with high-frequency power. [Background technology]

[0002] 2. Description of the Related Art Various techniques have been disclosed for protecting a high frequency amplifying device of a high frequency power source that outputs high power high frequency power in a high frequency processing apparatus.

[0003] For example, Patent Document 1 discloses a high-frequency power supply device equipped with a circulator placed on the output side of a power amplifier. In this high-frequency power supply device, the circulator guides reflected power to an absorbing resistor to prevent the reflected power from returning to the power amplifier, and the absorbing resistor absorbs the reflected power. This prevents damage to the power amplifier from the reflected power.

[0004] Patent Document 2 discloses a high-frequency power supply device equipped with an amplifying element having ferrite on the input and output sides. This high-frequency power supply device measures the temperature of the ferrite, and reduces or stops the output of the high-frequency power supply device when the temperature exceeds a threshold value. This prevents damage to the amplifying element in the high-frequency power supply device.

[0005] Patent Document 3 discloses a radio frequency power transmission circuit that includes a variable attenuation circuit connected to the output terminal of a power amplifier circuit and a reflected power detection circuit for detecting reflected power. This radio frequency power transmission circuit controls the attenuation of the variable attenuation circuit according to the magnitude of the reflected power so that reflected power exceeding a specified value does not return to the power amplifier circuit. This prevents damage to the amplifying element of the power amplifier circuit. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-048353 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-114982 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-166153 Summary of the Invention

[0007] Regarding Patent Document 1, circulators are technically the most effective means for preventing damage to power amplifiers. However, their physical shape depends on the wavelength of the radio waves. Therefore, while they are practical for microwave frequencies of several gigahertz, they are impractical for high-frequency band frequencies of several hundred megahertz or less. Furthermore, circulators are very expensive, which increases costs.

[0008] In both Patent Documents 2 and 3, the output of high frequency power is reduced or stopped to prevent damage to the amplifying element, which may result in a decrease in processing capacity.

[0009] An object of the present disclosure is to provide a high frequency processing apparatus that prevents damage to a high frequency amplifying device of a high frequency power source without reducing the output of high frequency power and has high processing performance.

[0010] A high-frequency processing apparatus according to one aspect of the present disclosure includes a high-frequency power source, a high-frequency power radiating unit, an impedance adjusting unit, a power detecting unit, and a control unit to perform high-frequency processing on an object.

[0011] The high-frequency power source generates high-frequency power of variable magnitude. The high-frequency power radiating unit radiates the high-frequency power toward an object. The impedance adjusting unit adjusts the load impedance for the high-frequency power source. The power detecting unit detects the power supplied from the high-frequency power source and the reflected power flowing back toward the high-frequency power source. The control unit controls the high-frequency power source and the impedance adjusting unit.

[0012] The control unit calculates a reflectance, which is a ratio of reflected power to supplied power, and a phase difference between the supplied power and reflected power. The control unit further controls the impedance adjustment unit to adjust the load impedance, thereby adjusting the reflectance and phase difference to predetermined values.

[0013] The high-frequency processing apparatus of the present disclosure can adjust the load impedance to prevent damage to the high-frequency amplification device of the high-frequency power source and maintain high processing performance without reducing the output power of the high-frequency power source, regardless of the type and condition of the object. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing a basic configuration of a high-frequency processing apparatus according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the configuration of a high-frequency power source of the high-frequency processing apparatus according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing a configuration of a power detection unit of the high frequency processing device according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating a circuit configuration of the impedance adjusting unit of the high-frequency processing apparatus according to the first embodiment. [Figure 5] FIG. 5 is a flowchart showing a basic control procedure of the high-frequency processing apparatus according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing an example of the output load characteristics of a high-power, high-frequency transistor. [Figure 7] FIG. 7 is a diagram showing the impedance region of the load normalized by the output impedance of the high frequency power source of the high frequency processing apparatus according to the first embodiment. [Figure 8A] FIG. 8A is a diagram for explaining impedance control in the output of the high-frequency power source by the impedance adjusting unit of the high-frequency processing apparatus according to the first embodiment. [Figure 8B]FIG. 8B is a diagram for explaining impedance control in the output of the high-frequency power source by the impedance adjusting unit of the high-frequency processing apparatus according to the first embodiment. [Figure 8C] FIG. 8C is a diagram illustrating impedance control in the output of the high-frequency power source by the impedance adjuster of the high-frequency processing apparatus according to the first embodiment. [Figure 9] FIG. 9 is a diagram showing a region to be avoided in a predetermined impedance region corresponding to the output power of the high frequency power source of the high frequency processing apparatus according to the first embodiment. [Figure 10] FIG. 10 is a block diagram showing a basic configuration of a high-frequency processing apparatus according to the second embodiment of the present disclosure. [Figure 11] FIG. 11 is a block diagram showing the configuration of a high-frequency power source of a high-frequency processing apparatus according to the second embodiment. [Figure 12] FIG. 12 is a diagram showing a predetermined impedance region of the output of the high frequency power source of the high frequency processing apparatus according to the second embodiment. [Figure 13A] FIG. 13A is a diagram illustrating impedance control in the output of a high-frequency power source by an impedance adjuster of the high-frequency processing apparatus according to the second embodiment. [Figure 13B] FIG. 13B is a diagram for explaining impedance control in the output of the high-frequency power source by the impedance adjusting unit of the high-frequency processing apparatus according to the second embodiment. [Figure 13C] FIG. 13C is a diagram illustrating impedance control in the output of the high-frequency power source by the impedance adjuster of the high-frequency processing apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] A high-frequency processing apparatus according to a first aspect of the present disclosure includes a high-frequency power source, a high-frequency power radiating unit, an impedance adjusting unit, a power detecting unit, and a control unit in order to perform high-frequency processing on an object.

[0016] The high-frequency power source generates high-frequency power of variable magnitude. The high-frequency power radiating unit radiates the high-frequency power toward an object. The impedance adjusting unit adjusts the load impedance for the high-frequency power source. The power detecting unit detects the power supplied from the high-frequency power source and the reflected power flowing back toward the high-frequency power source. The control unit controls the high-frequency power source and the impedance adjusting unit.

[0017] The control unit calculates a reflectance, which is a ratio of reflected power to supplied power, and a phase difference between the supplied power and reflected power. The control unit further controls the impedance adjustment unit to adjust the load impedance, thereby adjusting the reflectance and phase difference to predetermined values.

[0018] According to this aspect, it is possible to prevent damage to the high frequency amplifying device of the high frequency power source and maintain high processing performance without reducing the output of high frequency power.

[0019] If the RF power source does not include a circulator, the reflected power flows back toward the RF amplifier device. In this case, the voltage waveform and current waveform caused by the reflected power are superimposed on the normal voltage waveform and current waveform, respectively, inside the RF amplifier device. This changes the voltage waveform and current waveform inside the RF amplifier device.

[0020] As a result, voltage waveforms may overlap, increasing the amplitude, or the voltage and current waveforms may become distorted, resulting in an increase in the high frequency power consumed inside the high frequency amplifying device without being output to the outside.

[0021] Ideally, it is desirable to continuously adjust the load impedance and maintain a state in which no reflected power is generated. However, a certain amount of reflected power occurs depending on the type of load, fluctuations in load impedance during high-frequency processing, the accuracy of the detection circuit, etc. Therefore, it is important to appropriately control the reflectivity and phase difference.

[0022] In a high-frequency processing apparatus according to a second aspect of the present disclosure, in addition to the first aspect, the control unit determines whether the reflectance and phase difference are within a predetermined range corresponding to the output power of the high-frequency power source, and the control unit further causes the impedance adjustment unit to adjust the load impedance to bring the reflectance and phase difference within the predetermined range and maintain them.

[0023] According to this aspect, regardless of whether the output power of the high frequency power source increases or decreases, damage to the high frequency amplifying device of the high frequency power source can be prevented and high processing performance can be maintained.

[0024] In a high-frequency processing device according to a third aspect of the present disclosure, in addition to the first or second aspect, the control unit calculates the load impedance from the reflectance and the phase difference. The control unit determines whether the load impedance is located within a predetermined impedance region corresponding to the output power of the high-frequency power source on a Smith chart showing complex impedance. In this way, the control unit determines whether the reflectance and the phase difference are within the predetermined region.

[0025] The control unit further causes the impedance adjustment unit to guide and maintain the load impedance within the predetermined impedance region, thereby guiding and maintaining the reflectance and phase difference within the predetermined region.

[0026] According to this aspect, regardless of whether the output power of the high frequency power source increases or decreases, damage to the high frequency amplifying device of the high frequency power source can be prevented and high processing performance can be maintained.

[0027] In general, the output impedance and pass characteristics of a high-frequency amplifier device can vary depending on the output power. In particular, if the high-frequency power source does not include a circulator, the variation in the output impedance of the high-frequency amplifier device is linked to the variation in the output impedance of the high-frequency power source. For this reason, it is desirable to adjust the load impedance to a value appropriate for the output power.

[0028] In a high-frequency processing device according to a fourth aspect of the present disclosure, in addition to any of the first to third aspects, during execution of high-frequency processing on an object, the power detection unit detects supplied power and reflected power at predetermined time intervals or continuously, and the control unit calculates reflectance and phase difference.

[0029] According to this aspect, even if the state of the target object changes during high-frequency processing, the load impedance of the high-frequency power source can be maintained at a predetermined value, thereby preventing damage to the high-frequency amplifying device of the high-frequency power source and maintaining high processing performance without reducing the output of high-frequency power.

[0030] In a high-frequency processing apparatus according to a fifth aspect of the present disclosure, in addition to any of the first to fourth aspects, the control unit controls the impedance adjusting unit to adjust the load impedance so that the reflectance does not become equal to or lower than a predetermined threshold value.

[0031] According to this aspect, the load impedance value of the high frequency power source can be shifted to a range corresponding to the output power of the high frequency power source, and as a result, regardless of the type and state of the object, or changes in that state, the output power of the high frequency power source can be prevented from decreasing, and high processing performance can be maintained while preventing damage to the high frequency amplification device of the high frequency power source.

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0033] (Embodiment 1) 1 is a block diagram showing a basic configuration of a high-frequency processing device 1a according to a first embodiment of the present disclosure. As shown in FIG. 1, the high-frequency processing device 1a includes a high-frequency power source 10a, a power detection unit 20, an impedance adjustment unit 30, a high-frequency power emission unit 40, and a control unit 50a, and processes an object 60 with high-frequency power.

[0034] For the sake of simplicity, in this embodiment, the high-frequency processing device 1a has one high-frequency power source, one high-frequency power detector, one impedance adjuster, and one high-frequency power emitter, but the number of each is not limited to this.

[0035] High frequency power source 10a generates a high frequency signal, amplifies the high frequency signal to a level suitable for high frequency processing of target object 60, and outputs the amplified signal. Power detection unit 20 detects the supplied power and the reflected power, and outputs supplied power information T and reflected power information R to control unit 50a. The configurations of high frequency power source 10a and power detection unit 20 will be described later.

[0036] The supplied power is high-frequency power generated by the high-frequency power source 10a and supplied from the high-frequency power radiating unit 40 to the target 60 via the power detecting unit 20. The reflected power is high-frequency power that is reflected by the target 60 and flows back toward the high-frequency power source 10a via the high-frequency power radiating unit 40. The supplied power information T includes the magnitude and phase of the supplied power. The reflected power information R includes the magnitude and phase of the reflected power.

[0037] The control unit 50a outputs an impedance control signal IC, and uses this signal to control the impedance adjustment unit 30. The impedance adjustment unit 30 adjusts the impedance of the load as seen from the output terminal of the high-frequency power source 10a in accordance with the impedance control signal IC.

[0038] Hereinafter, the impedance of the load as seen from the output terminal of the high frequency power source will be referred to as the load impedance for the high frequency power source or simply as the load impedance. The value of the load impedance for the high frequency power source will be referred to as the load impedance value.

[0039] The impedance adjustment unit 30 is configured with a circuit including both or one of a variable inductance element and a variable capacitance element. The impedance adjustment unit 30 changes the value of both or one of the variable inductance element and the variable capacitance element in response to an impedance control signal IC. This adjusts the load impedance to a target impedance. The configuration of the impedance adjustment unit 30 will be described later.

[0040] The high frequency power radiating unit 40 radiates the high frequency power from the impedance adjusting unit 30 to the object 60. The high frequency power radiating unit 40 may be configured to radiate high frequency power to the object 60. For example, the high frequency power radiating unit 40 may be a radiating antenna such as a horn antenna, a pole antenna, or a patch antenna. The high frequency power radiating unit 40 may be configured to form a high frequency electric field between two parallel electrodes and treat the object 60 placed between the parallel electrodes.

[0041] The control unit 50a calculates the reflectivity and the phase difference based on the supplied power information T and the reflected power information R. The reflectivity is the ratio of the reflected power to the supplied power. The phase difference is the phase difference between the supplied power and the reflected power, and is the relative phase of the reflected power to the supplied power.

[0042] The control unit 50a calculates the load impedance from the calculated reflectance and phase difference, and causes the impedance adjusting unit 30 to adjust the load impedance based on the calculated reflectance and phase difference.

[0043] Fig. 2 is a block diagram showing the configuration of the high-frequency power source 10a. Fig. 2 also shows other components (power detection unit 20, control unit 50a) connected to the high-frequency power source 10a. As shown in Fig. 2, the high-frequency power source 10a has a high-frequency generating unit 11 and a power amplifying unit 12.

[0044] The high-frequency generating unit 11 is an oscillator that generates a high-frequency signal of any frequency in a predetermined frequency band. The high-frequency generating unit 11 may be configured, for example, as an XO (crystal oscillator) that uses a quartz crystal resonator and has a fixed frequency, or a VCO (voltage-controlled oscillator) whose oscillation frequency varies depending on a frequency control voltage. The high-frequency generating unit 11 may also be configured as a PLL (phase locked loop) that uses a phase comparator to lock the phase of the oscillator.

[0045] The power amplifier 12 amplifies the high frequency signal generated by the high frequency generator 11 and outputs high frequency power of a magnitude suitable for high frequency processing of the target object 60. The controller 50a controls the high frequency generator 11 and the power amplifier 12.

[0046] Fig. 3 is a block diagram showing the configuration of the power detection unit 20. Fig. 3 also shows other components (high-frequency power source 10a, impedance adjustment unit 30, and control unit 50a) connected to the power detection unit 20. As shown in Fig. 3, the power detection unit 20 has a supplied power detector 21, a reflected power detector 22, a supplied power detection unit 23, and a reflected power detection unit 24.

[0047] The supply power detector 21 branches off a portion of the high frequency power (supply power) generated by the high frequency power source 10a and supplied to the impedance adjustment unit 30. The supply power detector 21 outputs this branched portion of the supply power to the supply power detection unit 23 as detected supply power.

[0048] Reflected power detector 22 separates a portion of the high-frequency power (reflected power) flowing backward from impedance adjuster 30 toward high-frequency power source 10a. Reflected power detector 22 outputs this separated portion of the reflected power as detected reflected power to reflected power detector 24. Supply power detector 21 and reflected power detector 22 may be a directional coupler, a circulator, a hybrid coupler, or the like.

[0049] 3, the supplied power detector 21 and the reflected power detector 22 are depicted as separate entities. However, the supplied power detector 21 and the reflected power detector 22 may be configured, for example, as a directional coupler or a hybrid coupler, and may output the detected supplied power and the detected reflected power.

[0050] The supplied power detection unit 23 has a first amplitude detector 25 and a first phase detector 26. The detected supplied power separated by the supplied power detector 21 is input to the first amplitude detector 25 and the first phase detector 26. The reflected power detection unit 24 has a second amplitude detector 27 and a second phase detector 28. The detected reflected power separated by the reflected power detector 22 is input to the second amplitude detector 27 and the second phase detector 28.

[0051] The first amplitude detector 25 outputs a voltage value corresponding to the magnitude of the detected supplied power to the control unit 50a as supplied power amplitude information TM. The second amplitude detector 27 outputs a voltage value corresponding to the magnitude of the detected reflected power to the control unit 50a as reflected power amplitude information RM.

[0052] Specific configurations of the first amplitude detector 25 and the second amplitude detector 27 are well known. For example, the first amplitude detector 25 and the second amplitude detector 27 are configured by combining a rectifier circuit including a Schottky barrier diode and an integrator circuit including a resistor and a capacitor.

[0053] The first phase detector 26 outputs a voltage value corresponding to the phase of the detected supplied power to the control unit 50a as supplied power phase information TP. The second phase detector 28 outputs a voltage value corresponding to the phase of the detected reflected power to the control unit 50a as reflected power phase information RP.

[0054] The specific configurations of the first phase detector 26 and the second phase detector 28 are well known. For example, the first phase detector 26 and the second phase detector 28 are configured as quadrature detectors. The quadrature detector demodulates the input high-frequency signal by shifting the phase of the input high-frequency signal by 90 degrees. As a result, the quadrature detector outputs the in-phase component (I) voltage and quadrature component (Q) voltage of the waveform of the high-frequency signal as detection voltages.

[0055] The control unit 50a can calculate the phase of the high frequency signal using the in-phase component (I) voltage and the quadrature component (Q) voltage obtained from the quadrature detector. Specifically, the arc tangent (tan ) of the value obtained by dividing the in-phase component (I) voltage by the quadrature component (Q) voltage is -1 ) to calculate the phase of the high-frequency signal.

[0056] The control unit 50a calculates the phase value of the supplied power from the in-phase component (I) voltage and quadrature component (Q) voltage obtained from the first phase detector 26. The control unit 50a calculates the phase value of the reflected power from the in-phase component (I) voltage and quadrature component (Q) voltage obtained from the second phase detector 28. The control unit 50a calculates the difference between the two phase values ​​to calculate the relative phase of the reflected power with respect to the supplied power, i.e., the phase difference between the supplied power and the reflected power.

[0057] The amplitude can also be calculated from the root mean square of the in-phase component (I) voltage and the quadrature component (Q) voltage obtained from the quadrature detector. As a result, the first amplitude detector 25 and the first phase detector 26 may be configured as a single quadrature detector, and the second amplitude detector 27 and the second phase detector 28 may be configured as a single quadrature detector.

[0058] 3, the first amplitude detector 25 and the first phase detector 26 are depicted as separate entities. Supply power amplitude information TM is output from the first amplitude detector 25, and supply power phase information TP is output from the first phase detector 26. However, the first amplitude detector 25 and the first phase detector 26 may be configured as a single detector that performs amplitude detection and phase detection, and that outputs the supply power amplitude information TM and the supply power phase information TP.

[0059] The supplied power amplitude information TM and the supplied power phase information TP do not have to be two separate signals. A single signal may contain the supplied power amplitude information TM and the supplied power phase information TP. The same applies to the second amplitude detector 27 and the second phase detector 28.

[0060] Fig. 4 shows the circuit configuration of the impedance adjustment unit 30. Fig. 4 also shows other components connected to the impedance adjustment unit 30 (high-frequency power source 10a, power detection unit 20, high-frequency power emission unit 40, and control unit 50a).

[0061] 4, the impedance adjustment unit 30 has a variable inductance 31, a variable capacitance 32, a fixed capacitance 33, and a fixed inductance 34. The impedance adjustment unit 30 outputs the high-frequency power output from the power detection unit 20 to the high-frequency power emission unit 40.

[0062] An input terminal 35 of the impedance adjustment unit 30 is connected to the power detection unit 20, and an output terminal 36 of the impedance adjustment unit 30 is connected to the high-frequency power emission unit 40. The variable inductance 31 is connected to the input terminal 35 of the impedance adjustment unit 30, and the fixed inductance 34 is connected to the output terminal 36 of the impedance adjustment unit 30.

[0063] The fixed capacitance 33 is connected between the variable inductance 31 and the fixed inductance 34. One end of the variable capacitance 32 is connected between the variable inductance 31 and the fixed capacitance 33. The other end of the variable capacitance 32 is grounded.

[0064] The control unit 50a changes the inductance value of the variable inductance 31 and the capacitance value of the variable capacitance 32 by outputting an impedance control signal IC.

[0065] To change the inductance value of the variable inductance 31, for example, the coil length of the variable inductance 31 may be mechanically expanded or contracted. The inductance value of the variable inductance 31 may also be changed by changing the length of the inserted core material to change the magnetic permeability. The combined inductance value of the multiple fixed inductances may also be changed by switching the connection of multiple fixed inductances arranged in series or parallel with a switch.

[0066] To change the capacitance value of the variable capacitance 32, for example, a variable capacitor whose capacitance can be changed may be used. Alternatively, a variable capacitance diode whose capacitance value can be changed by the reverse bias voltage of the diode may be used. Alternatively, the combined capacitance value of multiple fixed capacitances may be changed by switching the connection of multiple fixed capacitances arranged in series or parallel using a switch.

[0067] The impedance adjustment unit 30 changes both or either the inductance value of the variable inductance 31 and the capacitance value of the variable capacitance 32 in response to the impedance control signal IC, thereby adjusting the load impedance of the power amplifier 12 of the high-frequency power source 10a shown in FIG. 2 to a target impedance.

[0068] 4 is an example of the circuit configuration of the impedance adjustment unit 30. The number, arrangement, connection order, etc. of the variable inductances, variable capacitances, fixed inductances, and fixed capacitances included in the impedance adjustment unit 30 are not limited to those in this embodiment.

[0069] As described above, according to the high-frequency processing device 1a of this embodiment, high-frequency power generated by the high-frequency power source 10a is radiated from the high-frequency power radiating unit 40 to the object 60 via the power detecting unit 20 and the impedance adjusting unit 30. In this way, processing of the object 60 is performed.

[0070] The power detection unit 20 detects the magnitude and phase of the supplied power and the magnitude and phase of the reflected power, and outputs the detected information to the control unit 50a. The control unit 50a outputs an impedance control signal IC to the impedance adjustment unit 30. The impedance adjustment unit 30 changes the load impedance for the high-frequency power source 10a in accordance with the impedance control signal IC.

[0071] Next, the operation of the high-frequency processing device 1a will be described. Fig. 5 is a flowchart showing the basic control procedure of the high-frequency processing device 1a. In the high-frequency processing device 1a, the control unit 50a performs the following processes.

[0072] 5, to start the heating process, the control unit 50a activates the high-frequency power source 10a to start outputting high-frequency power (step S1). The control unit 50a acquires supplied power information T and reflected power information R from the power detection unit 20 (step S2). The control unit 50a calculates the reflectance and the phase difference (step S3). The control unit 50a can calculate the reflectance from the ratio of the reflected power amplitude information RM to the supplied power amplitude information TM.

[0073] The control unit 50a determines whether the calculated reflectance and phase difference are predetermined reflectance and predetermined phase difference, respectively (step S4). This determination is made by determining whether the calculated reflectance is within a predetermined range for the reflectance and by determining whether the calculated phase difference is within a predetermined range for the phase difference.

[0074] The predetermined range for the reflectance and the predetermined range for the phase difference define a predetermined region for the reflectance and the phase difference. This predetermined region is defined corresponding to the output power of the high frequency power source 10a. The details of this predetermined region will be described later.

[0075] If the calculated reflectance and phase difference are within a predetermined range, the control unit 50a performs high-frequency processing on the object 60 (step S6). When this high-frequency processing is completed and the control unit 50a stops the output of high-frequency power from the high-frequency power source 10a (step S7), the high-frequency processing device 1a ends the high-frequency processing.

[0076] If either the calculated reflectance or phase difference is not within a predetermined range, the control unit 50a causes the impedance adjustment unit 30 to adjust the impedance of the input terminal 35 (step S5), thereby moving the reflectance and phase difference into the predetermined range for reflectance and phase difference.

[0077] Thereafter, the control unit 50a shifts the process to step S2, and repeats the processes of steps S2 to S5. Details of the control for guiding and maintaining the reflectance and phase difference within the predetermined range will be described later.

[0078] 5, high-frequency processing is performed on the target object 60 in step S6. However, strictly speaking, the emission of high-frequency power from the high-frequency power emission unit 40 begins when the high-frequency power source is activated in step S1. Furthermore, the high-frequency processing is performed on the target object 60 with high-frequency power obtained by subtracting reflected power and power consumption inside the impedance adjustment unit 30 from the supplied power.

[0079] Therefore, it can be considered that high-frequency processing is performed on the object 60 for the processing time in step S6 plus the processing time from the start of operation of the high-frequency power source in step S1 until it is determined in step S4 that both the reflectivity and phase difference have reached the predetermined values.

[0080] Here, the predetermined range for the reflectance and phase difference, and the control for guiding and maintaining the reflectance and phase difference within the predetermined range will be described.

[0081] When power amplifier 12 in high-frequency power source 10a includes an amplifying element such as a high-output high-frequency transistor, the impedance values ​​of the input and output terminals of the amplifying element are very low, on the order of a few ohms or less. For example, the input terminal of the amplifying element is the gate terminal of the transistor, and the output terminal of the amplifying element is the drain terminal of the transistor.

[0082] For this reason, an input matching circuit (not shown) is connected to the input terminal of the amplifying element, and an output matching circuit (not shown) is connected to the output terminal of the amplifying element, thereby matching the impedance of the input terminal of the amplifying element with the impedance of the circuit connected to the input terminal of the amplifying element, and matching the impedance of the output terminal of the amplifying element with the impedance of the circuit connected to the output terminal of the amplifying element.

[0083] Figure 6 shows an example of the output load characteristics of a high-power, high-frequency transistor. Figure 6 shows the drain efficiency and maximum output power values ​​for each output load state of the transistor, mapped as contour lines on a Smith chart.

[0084] As shown in Figure 6, the operation of a high-power, high-frequency transistor varies greatly depending on the load impedance state. In terms of drain efficiency, the highest drain efficiency is achieved in the impedance state shown at point 70. The drain efficiency at this point is 68%.

[0085] As the impedance state moves away from point 70, the drain efficiency value decreases in the order of 65% as indicated by contour line 71, 63% as indicated by contour line 72, 60% as indicated by contour line 73, and 56% as indicated by contour line 74.

[0086] In terms of maximum output power, the maximum output power is obtained in the impedance state at point 75. The maximum output power at this time is 51 dBm. As the impedance state moves away from point 75, the maximum output power value decreases in the order of 50 dBm shown by contour line 76, 48 dBm shown by contour line 77, 46 dBm shown by contour line 78, and 44 dBm shown by contour line 79.

[0087] As shown in Figure 6, there is a trade-off between drain efficiency and output power. When designing an amplifier, it is necessary to design the input matching circuit and output matching circuit so that the load impedance is appropriate, taking into account the balance between the desired output power and drain efficiency. In particular, drain efficiency is closely related to the power consumption of the transistor. For this reason, care must be taken to avoid high-output operation when drain efficiency is low.

[0088] 7 is a Smith chart showing the impedance region of the load normalized by the output impedance (50Ω in this disclosure) of the high-frequency power source 10a. In FIG. 7, a predetermined impedance region 80 (shaded area) indicates a desirable range of load impedance values ​​corresponding to the output power of the high-frequency power source 10a.

[0089] That is, if the load impedance value is maintained within the predetermined impedance region 80 during high frequency processing, the high frequency transistor of the power amplifier unit 12 can operate without damage at a desired output power suitable for high frequency processing of the target object 60. The predetermined impedance region 80 is determined based on the output load characteristics of the high frequency transistor shown in FIG.

[0090] The Smith chart is a circular chart showing complex impedances used in impedance matching design. The center of the Smith chart indicates the load impedance value at which no reflected power occurs.

[0091] In this disclosure, the output impedance of the high-frequency power source 10a is 50 Ω, so the center of the Smith chart indicates a load impedance value of 50 Ω. The reflectivity increases with distance from the center, and the outer periphery indicates a load impedance value at which total reflection occurs.

[0092] The Smith chart expresses the load impedance value by the distance from the center to any point on the chart and the angle between a line extending left from the center and the line segment from the center to that point. The distance corresponds to the magnitude of the reflection coefficient, and the angle corresponds to the relative phase of the reflected power to the supplied power.

[0093] 8A to 8C, an example of how the impedance adjuster 30 controls the load impedance of the high-frequency power source 10a will be described. 8A to 8C are Smith charts for illustrating the impedance control of the output of the high-frequency power source 10a by the impedance adjuster 30.

[0094] As described above, the control unit 50a acquires the supplied power information T and the reflected power information R from the power detection unit 20 (step S2 in FIG. 5). The control unit 50a calculates the reflectance and the phase difference from the supplied power information T and the reflected power information R (step S3 in FIG. 5). The reflectance and the phase difference are values ​​that correspond to the load impedance.

[0095] 8A, the load impedance value is located within a predetermined impedance region 80 corresponding to the output power at that time. In this case, adjustment of the load impedance value by the impedance adjusting unit 30 is not required.

[0096] As described above, the control unit 50a calculates the load impedance value from the reflectance and the phase difference. Therefore, the control unit 50a determines the position of the load impedance value on the Smith chart shown in FIG. 7, etc., based on the reflectance and the phase difference.

[0097] When the calculated impedance value is indicated by point B in Fig. 8B, the load impedance value is outside the predetermined impedance region 80 corresponding to the output power at that time. In this case, the control unit 50a controls the impedance adjustment unit 30 so that the load impedance value moves into the predetermined impedance region 80 (point A in Fig. 8B).

[0098] While high-frequency processing is being performed on the object 60, the control unit 50a performs the processing of steps S2 to S4 in Figure 5 at predetermined time intervals or continuously, and determines whether the load impedance value is located within the predetermined impedance region 80.

[0099] If the load impedance value is located within a predetermined impedance region 80 corresponding to the output power at that time, the control unit 50a causes the impedance adjustment unit 30 to adjust the load impedance value so as to maintain the load impedance value within the predetermined impedance region 80.

[0100] For example, when the load impedance value is within a predetermined impedance region 80 corresponding to the output power at that time (point A in FIG. 8C), high-frequency processing of the object 60 may change the impedance of the object 60, causing the load impedance value to move outside the predetermined impedance region 80 (point B in FIG. 8C).

[0101] In this case, the control unit 50a controls the impedance adjusting unit 30 to move the load impedance value into the predetermined impedance region 80 (point C in FIG. 8C). That is, the reflectance and the phase difference can be adjusted to a predetermined reflectance corresponding to the output power and a predetermined phase difference corresponding to the output power, respectively.

[0102] As a result, the high-frequency processing device 1a can perform high-frequency processing on the object 60 while the load impedance value is maintained within a predetermined impedance region 80 corresponding to the output power at that time.

[0103] 9 is a diagram showing a region to be avoided in a predetermined impedance region corresponding to the output power of the high-frequency power source 10a. The control unit 50a sets the region shown by the diagonal lines in FIG. 9 as a predetermined impedance region 83 so that the reflectance does not fall within region 82 shown by the dashed line in FIG. 9. Region 82 is a region where the reflectance is equal to or less than a predetermined threshold. In other words, the control unit 50a controls the impedance adjustment unit 30 so as to maintain the load impedance value within the predetermined impedance region corresponding to the output power at that time without excessively reducing the reflectance.

[0104] This improves the detection accuracy of the first phase detector 26 and the second phase detector 28 in the power detection section 20. As a result, the reflectance and phase difference can be calculated more accurately.

[0105] (Embodiment 2) Hereinafter, the second embodiment of the present disclosure will be described, focusing on the differences from the first embodiment. In the present embodiment, the same or substantially identical components as those in the first embodiment will be denoted by the same reference numerals, and the description thereof may be omitted.

[0106] FIG. 10 is a block diagram showing a basic configuration of a high-frequency processing device 1b according to the second embodiment of the present disclosure.

[0107] 10, the high-frequency processing device 1b includes a high-frequency power source 10b instead of the high-frequency power source 10a, and a control unit 50b instead of the control unit 50a. The configurations of the power detection unit 20, the impedance adjustment unit 30, and the high-frequency power emission unit 40 are the same as those in the first embodiment.

[0108] Fig. 11 is a block diagram showing the configuration of high-frequency power source 10b. Fig. 11 also shows other components (power detection unit 20, control unit 50b) connected to high-frequency power source 10b. As shown in Fig. 11, high-frequency power source 10b has high-frequency generation unit 11, power variation unit 13, and power amplification unit 12. The configurations of high-frequency generation unit 11 and power amplification unit 12 are the same as those in the first embodiment.

[0109] The power variable unit 13 is a variable attenuator that attenuates the high-frequency signal from the high-frequency generating unit 11 in response to a control signal from the control unit 50b. The specific configuration of the power variable unit 13 is well known. The power variable unit 13 may be, for example, a multi-bit step variable attenuator such as a FET (field effect transistor) switch circuit network, or a continuously variable attenuator such as a PIN diode network.

[0110] In this embodiment, the power variable unit 13 is a variable attenuator. However, the power variable unit 13 may also be a variable gain amplifier. In Fig. 11, the power variable unit 13 and the power amplifier unit 12 are configured as separate units. However, the power variable unit 13 and the power amplifier unit 12 may also be configured as a single variable gain power amplifier circuit.

[0111] With this configuration, the high-frequency processing device 1b can perform high-frequency processing on the object 60 by irradiating the object 60 with high-frequency power of any magnitude according to the purpose of the processing.

[0112] Also, similar to the first embodiment, the power detection unit 20 detects the supplied power and the reflected power, and outputs supplied power information T and reflected power information R to the control unit 50b. The control unit 50b outputs an impedance control signal IC to the impedance adjustment unit 30. The impedance adjustment unit 30 changes the load impedance for the high-frequency power source 10b in accordance with the impedance control signal IC.

[0113] In the present embodiment, reflected power is defined as the high-frequency power, of the supplied power, that is reflected by the object 60 and flows back toward the high-frequency power source 10a via the high-frequency power radiating unit 40. However, high-frequency power that flows back toward the high-frequency power source 10b due to other factors may also be defined as reflected power.

[0114] For example, the power detecting unit 20 may detect, as reflected power, high-frequency power that is not emitted from the high-frequency power emitting unit 40 but is reflected by the high-frequency power emitting unit 40 and flows backward. The power detecting unit 20 may also detect, as reflected power, high-frequency power that is not incident on the impedance adjusting unit 30 but is reflected by the impedance adjusting unit 30 and flows backward. Furthermore, the power detecting unit 20 may separately detect only the reflected power from one of the reflecting surfaces, or may detect all the reflected power from all the reflecting surfaces as reflected power.

[0115] The operation of the high-frequency processing device 1b described above will be explained, focusing on the differences from the operation of the high-frequency processing device 1a of the first embodiment.

[0116] In the high frequency processing device 1b, similarly to the high frequency processing device 1a, the control unit 50b calculates the reflectance and phase difference from the supplied power information T and the reflected power information R, that is, the load impedance value for the high frequency power source 10b.

[0117] Based on this result, the control unit 50b causes the impedance adjusting unit 30 to move the load impedance value into a predetermined impedance region that corresponds to the magnitude of the supplied power.

[0118] 12 is a diagram showing three predetermined impedance regions 84, 85, and 86 at the output of the high frequency power source 10b. These predetermined impedance regions are determined according to the magnitude of the supplied power.

[0119] That is, predetermined impedance region 84 corresponds to a case where the output power is low (e.g., 200 W). Predetermined impedance region 85 corresponds to a case where the output power is medium (e.g., 500 W). Predetermined impedance region 86 corresponds to a case where the output power is high (e.g., 800 W). When the load impedance is maintained within the predetermined impedance region corresponding to the output power at that time, the high-frequency transistors of power amplifier section 12 can operate without being damaged.

[0120] 12, the predetermined impedance region 84 includes a predetermined impedance region 85 and a predetermined impedance region 86. The predetermined impedance region 85 includes the predetermined impedance region 86.

[0121] 13A to 13C, how control unit 50b causes impedance adjustment unit 30 to adjust the load impedance for high-frequency power source 10b will be described. Figures 13A to 13C are diagrams for explaining impedance control of the output of the high-frequency power source by impedance adjustment unit 30.

[0122] As in the first embodiment, the control unit 50b acquires the supplied power information T and the reflected power information R from the power detection unit 20. The control unit 50b calculates the reflectance and the phase difference. These values ​​correspond to the load impedance value.

[0123] When the calculated impedance value is indicated by point A in Fig. 13A, the load impedance value is outside the predetermined impedance region 84. In this case, the control unit 50b needs to cause the impedance adjustment unit 30 to adjust the load impedance to move the load impedance value in Fig. 13A.

[0124] The load impedance value moves to a predetermined impedance region corresponding to the magnitude of the supplied power. That is, when the magnitude of the supplied power is low (for example, when the output is 200 W), the load impedance value moves from point A in Fig. 13A to point B, point C, or point D in Fig. 13A. In Fig. 13A, points B, C, and D are located in predetermined impedance region 84, predetermined impedance region 85, and predetermined impedance region 86, respectively.

[0125] When the magnitude of the supplied power is medium (for example, when the output is 500 W), the load impedance value moves from point A in Fig. 13A to point C or point D in Fig. 13A. When the magnitude of the supplied power is high (for example, when the output is 800 W), the load impedance value moves from point A in Fig. 13A to point D in Fig. 13A.

[0126] As another example, when a similarly calculated impedance value is indicated by point E in Fig. 13B, the load impedance value is within the predetermined impedance region 85. Therefore, when the magnitude of the supplied power is medium power or less, the control unit 50b does not need to cause the impedance adjustment unit 30 to adjust the load impedance value.

[0127] When the magnitude of the high-frequency power radiated from the high-frequency power radiating unit 40 to the target object 60 is high (e.g., 800 W), the control unit 50b controls the impedance adjusting unit 30 so that the calculated load impedance value moves to the predetermined impedance region 86 (point F in Figure 13B).

[0128] As another example, when a similarly calculated load impedance value is shown at point G in Fig. 13C, the load impedance value is within predetermined impedance region 85. In this case, the impedance state of object 60 changes while high-frequency processing is being performed on object 60. As a result, the load impedance value moves into predetermined impedance region 84 (point H in Fig. 13C).

[0129] In this case, the control unit 50b controls the impedance adjusting unit 30 so that the load impedance moves into the predetermined impedance region 85 (point J in FIG. 13C).

[0130] As in the first embodiment, while high-frequency processing is being performed on the target object 60, the control unit 50b performs the processing of steps S2 to S4 of FIG. 5 at predetermined time intervals or continuously, and determines the relationship between the load impedance value and the predetermined impedance regions 84, 85, and 86 corresponding to the magnitude of the supplied power.

[0131] When the load impedance value is located in any of the predetermined impedance regions 84, 85, and 86, the control unit 50a controls the impedance adjusting unit 30 so that the load impedance value is maintained within the predetermined impedance region corresponding to the magnitude of the supplied power.

[0132] According to this embodiment, the reflectance and the phase difference can be adjusted to a predetermined reflectance corresponding to the output power and a predetermined phase difference corresponding to the output power, respectively.

[0133] As shown in FIG. 12, when the allowable high-frequency power value varies depending on the load impedance value, the power may be increased within the allowable range during impedance adjustment to shorten the time from the start to the end of high-frequency processing.

[0134] For example, when the target object 60 is subjected to high-frequency processing at 800 W in step S6, when the load impedance value shown in FIG. 13A enters the predetermined impedance region 84 in the process of moving from point A to point D, the control unit 50b sets the high-frequency output to the maximum power value (e.g., 200 W) allowed in the predetermined impedance region 84.

[0135] Furthermore, when the load impedance value falls within a predetermined impedance region 85, the control unit 50b sets the high-frequency output to the maximum power value (e.g., 500 W) allowed within the predetermined impedance region 85. When the load impedance value falls within a predetermined impedance region 86, the control unit 50b may set the high-frequency output to 800 W, proceed to step S6 shown in FIG. 5, and perform high-frequency processing on the target object 60.

[0136] 7, when the predetermined impedance range is wide and allows for a range from no reflection to total reflection or a state close to total reflection, the control unit 50b may control only the phase. To improve the efficiency of high-frequency processing, the control unit 50b may control the phase to a predetermined value while reducing the reflected power to a predetermined value or less. [Industrial Applicability]

[0137] The present disclosure is useful for microwave ovens, dryers, and other appliances that utilize electromagnetic waves, and is capable of preventing damage to a high-frequency amplification device of a high-frequency power source and maintaining high processing performance without reducing the output of high-frequency power in a high-frequency processing apparatus. [Explanation of symbols]

[0138] 1a, 1b High frequency processing device 10a, 10b High frequency power source 11 High frequency generator 12 Power amplifier section 13 Variable power unit 20 Power detection unit 21 Supply power detector 22 Reflected Power Detector 23 Power supply detection section 24 Reflected power detector 25 First amplitude detector 26 First phase detector 27 Second amplitude detector 28 Second Phase Detector 30 Impedance adjustment section 31 Variable inductance 32 Variable Capacitance 33 Fixed Capacitance 34 Fixed inductance 35 Input terminal 36 Output terminal 40 High frequency power radiation section 50a, 50b Control section 60 Objects 70, 75 points 71, 72, 73, 74, 76, 77, 78, 79 Contour lines 80, 83, 84, 85, 86 Predetermined impedance region 82 areas

Claims

1. A high-frequency processing device, a high frequency power source that generates high frequency power of variable magnitude; a high frequency power radiating unit that radiates the high frequency power to an object; an impedance adjusting unit that adjusts a load impedance for the high frequency power source; a power detection unit that detects power supplied from the high frequency power source and power reflected back toward the high frequency power source; a control unit that controls the high-frequency power source and the impedance adjustment unit; Equipped with the control unit calculates a reflectance, which is a ratio of the reflected power to the supplied power, and a phase difference between the supplied power and the reflected power, and calculates a load impedance from these. A high-frequency processing apparatus characterized by controlling the impedance adjustment unit so that the load impedance is guided and maintained within a predetermined impedance region predefined in accordance with the output power of the high-frequency power source, and further controlling the impedance adjustment unit so that the reflectivity does not become equal to or lower than a predetermined threshold.

2. In the high-frequency processing apparatus according to claim 1, 10. A high frequency processing apparatus, comprising: a power amplifier section for amplifying a high frequency power source; a power amplifier for amplifying a high frequency power source; a power amplifier for amplifying a high frequency power source; a power amplifier section for amplifying a high frequency power source;

3. In the high-frequency processing apparatus according to claim 2, A high-frequency processing apparatus comprising a control unit that increases the output power when the load impedance reaches a predetermined impedance region corresponding to a certain power level, and immediately decreases the output power when the load impedance falls outside that region.

4. 2. The high-frequency processing apparatus according to claim 1, wherein the power detection unit is configured to detect the supplied power and the reflected power at predetermined time intervals or continuously while high-frequency processing is being performed on the object, and the control unit is operable to calculate the reflectivity and the phase difference.

5. The high-frequency processing apparatus according to claim 1 , wherein the control unit is operable to cause the impedance adjustment unit to adjust the load impedance so that the reflectance does not become equal to or lower than a predetermined threshold value.

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