Oscillator and phase detection method

Abstract

To detect the phase difference between signals with high precision. [Solution] The oscillator comprises a signal generation unit, an analog detection device, an adjustment unit, and a waveform control unit. The signal generation unit outputs multiple high-frequency signals whose phase and level can be individually controlled. The analog detection device detects the relative phase difference and level ratio of the multiple high-frequency signals and outputs a detection signal. The adjustment unit adjusts the phase and level of at least one of the multiple high-frequency signals input to the analog detection device so that the relative phase difference of the multiple high-frequency signals input to the analog detection device falls within a predetermined range. The waveform control unit controls the phase and level of the multiple high-frequency signals based on a set value related to the temperature environment inside the furnace, a sensor value from a sensor that detects the state of the object inside the furnace, and the detection signal.

Description

Technical Field

[0001] Embodiments of the present invention relate to an oscillator and a phase detection method.

Background Art

[0002] Devices that irradiate high-frequency waves to heat an object are widely used from the household to the industrial fields. Large-scale devices are used in factories for drying agricultural products, cooking food materials, or melting semiconductors to create the material (ingot) before cutting wafers.

[0003] For example, high-frequency waves in the 2.45 GHz band are often used. An oscillator that generates a continuous waveform CW (Continuous Wave) signal instead of a pulsed waveform is known to use a power semiconductor to enable variable control of the output level and phase instead of the conventional magnetron. By combining multiple such oscillators and adjusting the phase and level of the output of each oscillator to cause radio wave interference, the temperature inside the furnace where the object is placed can be controlled two-dimensionally or three-dimensionally.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0006] Therefore, the object of the present invention is to provide an oscillator and a phase detection method that can detect the phase difference between signals with high accuracy, regardless of the phase difference or output level of the output signals of multiple oscillators. [Means for solving the problem]

[0007] According to the embodiment, the oscillator generates a high frequency to heat an object in the furnace. The oscillator comprises a signal generation unit, an analog detection device, an adjustment unit, and a waveform control unit. The signal generation unit outputs multiple high frequencies whose phase and level can be individually controlled. The analog detection device detects the relative phase difference and level ratio of the multiple high frequencies and outputs a detection signal. The adjustment unit adjusts the phase and level of at least one of the multiple high frequencies input to the analog detection device so that the relative phase difference of the multiple high frequencies input to the analog detection device falls within a predetermined range. The waveform control unit controls the phase and level of the multiple high frequencies based on a set value related to the temperature environment inside the furnace, a sensor value from a sensor that detects the state of the object inside the furnace, and the detection signal. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing an example of an oscillator according to the embodiment. [Figure 2] Figure 2 is a block diagram showing an example of the transmitting amplifier 30 shown in Figure 1. [Figure 3]Figure 3 is a system diagram showing an example of the oscillator shown in Figure 1. [Figure 4] Figure 4 is a functional block diagram showing an example of the processor 1 and memory 2 shown in Figure 1. [Figure 5] Figure 5 shows an example of the characteristic curve of the phase-level detector 8. [Modes for carrying out the invention]

[0009] Figure 1 is a block diagram showing an example of an oscillator according to the embodiment. In this embodiment, an oscillator that generates microwaves as an example of high frequency is assumed. However, the high frequency band is not limited to the microwave band as long as it can produce a heating effect. In Figure 1, the master oscillator 10 comprises a processor 1 and a memory 2, a signal generation unit 3, an amplification unit 4, a distributor 5, a phase adjuster 6, a level adjuster 7, and a phase / level detector 8. The master oscillator 10 is also connected to the control unit 9 and the sensor 70. The control unit 9 is an interface that accepts user input and is used, for example, to set the temperature environment inside the furnace 50. The sensor 70 detects the state of the object inside the furnace 50 and notifies the processor 1.

[0010] The signal generation unit 3 generates two microwaves, each with independently controllable phase and level. One of these microwaves is input to the transmitting amplifier 30, while the other microwave is input to the slave oscillator 21.

[0011] In the master oscillator 10, one microwave is level-adjusted in the amplification unit 4 and then split into two by the distributor 5. One is input to the transmitting amplifier 30, and the other to the phase adjuster 6. The phase adjuster 6, together with the level adjuster 7, forms an adjustment unit and adjusts the phase and level of the microwave from the distributor 5. The phase / level-adjusted microwave is input to the phase / level detector 8, which is an analog detection device.

[0012] The slave oscillator 21 adjusts the level of the input microwave in the amplification unit 4 and splits it into two parts in the distributor 5, sending one part to the transmitting amplifier 30 and the other part back to the phase / level detector 8 of the master oscillator 10.

[0013] The phase / level detector 8 receives its own microwave, which has been phase / level adjusted within the master oscillator 10, and the microwave from the slave oscillator 21 as inputs, detects the relative phase difference and level ratio between them, and outputs a detection signal. This detection signal is converted into data by an analog-to-digital converter (not shown) and notified to the processor 1.

[0014] Figure 2 is a block diagram showing an example of the transmitting amplifier 30 shown in Figure 1. In Figure 2, the microwave input to the transmitting amplifier 30 is split into multiple signals by a demultiplexer 31, each amplified individually by a power amplifier 32, and then combined by a power combiner 33. This results in a relatively high power level of several tens of dBm.

[0015] Figure 3 is a system diagram showing an example of the oscillator shown in Figure 1. This device heats an object placed inside a reactor (furnace) by irradiating it with high-frequency microwaves. In this embodiment, it is assumed that the phase and level of the microwaves output from multiple oscillators are adjusted while checking the state of the object to be heated. As shown in Figure 3, for example, two oscillators are installed in a pair inside the furnace, and the temperature at various points inside the furnace can be adjusted by individually adjusting the phase and level of the microwaves from each oscillator. In other words, the temperature environment can be freely controlled.

[0016] Here, the temperature environment refers to the environment that can be realized by microwave energy, such as the location of the object being heated inside the furnace 50, the heating temperature, and the temperature change curve. In this embodiment, high frequencies in the microwave band will be used for explanation. Other frequency bands may also be used as long as the object can be heated.

[0017] In FIG. 3, a plurality of areas (Area 1 to Area X) are set in the place where the device is installed, and a microwave irradiation system is constructed for each area. One microwave irradiation system includes two power feeding points (antennas) 40 that open into the furnace 50, a master oscillator 10, and a slave oscillator 21. The transmission amplifier 30 in FIG. 1 is connected to the power feeding points 40 in the master oscillator 10 and the slave oscillator 21 to form a radiation unit, which amplifies the microwave power and radiates it into the furnace 50 from the power feeding points 40.

[0018] The master oscillator 10 generates two systems of microwaves. One system of microwaves is input into the transmission amplifier 30 in the master oscillator 10, and the other system of microwaves is input into the slave oscillator 21. The state of the object in the furnace 50 is detected by the sensor 70, and the obtained sensor value is input into the master oscillator 10. Here, the state of the object is a quantity that can be detected by the sensor 70, such as the overall temperature of the object, the partial temperature, the temperature change rate, or the degree of drying.

[0019] FIG. 4 is a functional block diagram showing an example of the processor 1 and the memory 2 shown in FIG. 1. The processor 1 includes a waveform control unit 1a and an adjustment processing unit 1b as processing functions according to the embodiment. The memory 2 stores a set value 2a related to the temperature environment set via the operation unit 9, a sensor value 2b of the sensor 70, a phase difference information 2c based on the detection signal from the phase / level detector 8, an initial state value 2d based on the detection signal in the initial state, and a program 2e. The program 2e includes instructions for causing the processor 1 to function as the waveform control unit 1a and the adjustment processing unit 1b.

[0020] In FIG. 4, the waveform control unit 1a performs feedback control on the phase and level of the micromicrowaves output from the master oscillator 10 and the slave oscillator 21 based on the set value 2a, the sensor value 2b, and the phase difference information 2c (the dotted line in FIG. 1).

[0021] The adjustment processing unit 1b variably controls the phase adjustment amount of the phase adjuster 6 and the level adjustment amount of the level adjuster 7 so that the relative phase difference of the two microwaves input to the phase-level detector 8 falls within a predetermined range. The adjustment processing unit 1b controls the phase adjuster 6 and the level adjuster 7 to realize their function as adjustment units. In this embodiment, as an example of the predetermined range, the angular range with respect to phase is set to 90 [deg] ± 45 [deg]. This will be explained with reference to Figure 5.

[0022] Figure 5 shows an example of the characteristic curve of the phase-level detector 8. The horizontal axis of the graph shown in Figure 5 represents the relative phase difference between the two input microwaves. The upward-convex curve represents the intensity of the phase detection signal (in units [V]). This phase detection signal is a detection signal that represents the relative phase difference (and level ratio) between the two input microwaves, and is maximum at the point where the phase difference is zero (center of the horizontal axis). The phase detection error is represented on the axis to the right of the graph, and becomes unmeasurable when the relative phase difference between the two microwaves is zero or near ±180 [deg].

[0023] In this embodiment, the phase adjustment amount of the phase adjuster 6 and the level adjustment amount of the level adjuster 7 are controlled so as to use an angular range in which the phase detection error is nearly flat. In the analog detection device according to this embodiment, an approximately accurate output can be obtained if the phase difference between the two input signals is within an angular range of 90 degrees ± 45 degrees in terms of phase. Therefore, in this embodiment as well, this angular range (the range enclosed by the dashed line) is set as the default angular range. If a detection device that can obtain an accurate output in a different phase range is used, the control may be made to fall within the phase range for that detection device.

[0024] As described above, in this embodiment, when two microwaves are input to the phase / level detector 8 to detect the phase difference and level difference, the set value 2a of each microwave, the initial state value 2d which is the phase information in the initial state, and the sensor value 2b which indicates the current state of the device (temperature, frequency, etc.) are acquired. Then, the phase adjustment amount of the phase adjuster 6 and the level adjustment amount of the level adjuster 7 are variably controlled so that the relative phase difference of the two microwaves input to the phase / level detector 8 falls within a predetermined range. In this way, the phase / level detector 8, which is an analog detection device, can be driven at the optimal operating point, and therefore the phase difference between microwaves can be measured with high precision. This makes it possible to control the temperature environment inside the furnace 50 with high precision, and consequently, to finely control the heating temperature of the object.

[0025] In particular, by incorporating phase information in the initial state, it becomes possible to correctly select which part of the graph, such as the one shown in Figure 5, to use. In other words, since the characteristic curve in Figure 5 is symmetrical, it is necessary to decide whether to use the right half or the left half. Therefore, by slightly changing the phase in the initial state and checking the amount of voltage change, it is possible to understand which side the relative phase difference lies in, and accurate control can be achieved. As a method to freely switch between the range of the right half and the left half, this can be achieved, for example, by using a 90° hybrid.

[0026] Furthermore, according to this embodiment, the accuracy of phase detection using a relatively inexpensive analog detection device can be improved, thus resolving the trade-off between cost and accuracy and suppressing the increase in system costs.

[0027] Based on these findings, it becomes possible to provide an oscillator and a phase detection method that can detect the phase difference between signals with high precision, regardless of the phase difference or output level of the output signals of multiple oscillators. Consequently, it becomes possible to control the temperature environment inside the furnace with high precision, and to control the location (heating point) and temperature of the object to be heated with high precision.

[0028] It should be noted that this invention is not limited to the above-described embodiment. For example, in this embodiment, two oscillators are provided, and the phase and level of the microwaves output from each oscillator are controlled individually. With at least two oscillators, it is possible to create any temperature environment inside the furnace by interfering the two microwaves output from each oscillator. Of course, three or more oscillators may be used to generate three, four, five or more microwaves.

[0029] For example, when using three microwaves, the signal generation unit 3 of the master oscillator 10 generates three separate microwave systems (system 1, system 2, and system 3), each with individually controllable phase and level. Of these, the microwave from system 1 is input to its own amplification unit 4, while the microwaves from systems 2 and 3 are input to one of the multiple slave oscillators 21. The phase / level detector 8 takes its own microwave and a microwave from one of the multiple slave oscillators 21 as input, detects the relative phase difference and level ratio between them, and outputs a detection signal.

[0030] In this case, it is advisable to provide a changeover switch (SW) for switching between the microwaves from multiple slave oscillators 21. In other words, the microwaves from multiple slave oscillators 21 are selectively switched using the changeover switch and input to the master oscillator 10. By providing a changeover switch, the microwave outputs from each of the multiple slave oscillators 21 can be controlled / managed sequentially.

[0031] The adjustment processing unit 1b variably controls the phase adjustment amount of the phase adjuster 6 and the level adjustment amount of the level adjuster 7 so that the relative phase difference of the two microwaves input to the phase / level detector 8 falls within a predetermined range.

[0032] The waveform control unit 1a provides feedback control of the phase and level of the microwaves output from the master oscillator 10 and the slave oscillator 21, respectively, based on the set value 2a, the sensor value 2b, and the phase difference information 2c.

[0033] Furthermore, in Figure 1, only the master oscillator 10 is equipped with a phase adjuster 6 and a level adjuster 7 to adjust the phase / level of the microwaves in the master oscillator 10 that are input to the phase / level detector 8. Instead of this example which targets only one microwave system, the phase adjuster 6 and level adjuster 7 may also be provided on the slave oscillator 21 to adjust the phase and level of both microwave systems.

[0034] Furthermore, although Figure 1 shows the signal generation unit 3, phase adjuster 6, and level adjuster 7 as separate components, it is also possible to combine them into a single unit. For example, if the signal generation unit 3 is configured with a digital control signal generation element (e.g., DDS: Direct Digital Synthesizer) having multiple output channels and a digital-to-analog converter, it becomes possible to directly generate multiple microwave signals with phase and level adjustment. In other words, the phase adjuster 6 and level adjuster 7 can be provided as functions of the signal generation unit 3.

[0035] While embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications are permitted without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the claims and their equivalents. [Explanation of Symbols]

[0036] 1...Processor, 1a...Waveform control unit, 1b...Adjustment processing unit, 2...Memory, 2a...Setting value, 2b...Sensor value, 2c...Phase difference information, 2d...Initial state value, 2e...Program, 3...Signal generation unit, 4...Amplifier unit, 5...Distributor, 6...Phase adjuster, 7...Level adjuster, 8...Phase / level detector, 9...Operation unit, 10...Master oscillator, 15...Changeover switch, 21...Slave oscillator, 30...Transmitting amplifier, 31...Demultiplexer, 32...Power amplifier, 33...Power combiner, 40...Feed point, 50...Furnace, 70...Sensor.

Claims

1. An oscillator that generates high-frequency waves to heat an object inside a furnace, A storage unit that stores set values ​​related to the temperature environment inside the furnace, A signal generation unit that outputs multiple high-frequency signals with individually controllable phase and level, An analog detection device that detects the relative phase difference and level ratio of multiple high-frequency systems and outputs a detection signal, An adjustment unit that adjusts the phase and level of at least one of the multiple high-frequency signals input to the analog detection device so that the relative phase difference of the multiple high-frequency signals input to the analog detection device falls within a predetermined range, A waveform control unit that controls the phase and level of the multiple high-frequency systems based on the set value, the sensor value of the sensor that detects the state of the object, and the detection signal, An oscillator equipped with the following features.

2. The oscillator according to claim 1, wherein the adjustment unit controls the phase adjustment amount and the level adjustment amount of the adjustment unit based on the initial detection signal output from the analog detection device.

3. The oscillator according to claim 1, wherein the predetermined range is an angular range of 90 degrees ± 45 degrees with respect to phase.

4. The signal generating unit is The aforementioned digital control signal generating element and digital-to-analog converter that generate multiple high-frequency systems, The oscillator according to claim 1, further comprising the adjustment unit.

5. A phase detection method comprising an analog detection device that detects the relative phase difference and level ratio of multiple high-frequency signals and outputs a detection signal, and performed by an oscillator that generates a high-frequency signal to heat an object in a furnace, The oscillator performs a process of adjusting the phase and level of at least one of the multiple high-frequency signals so that the relative phase difference of the multiple high-frequency signals input to the analog detection device falls within a predetermined range. The oscillator controls the phase and level of the multiple high-frequency systems based on a set value related to the temperature environment inside the furnace, a sensor value from a sensor that detects the state of an object inside the furnace, and the detection signal. A phase detection method comprising the following:

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