RF Energy Radiation Devices

Abstract

The RF energy radiating device includes a cavity for placing an object to be heated, an RF signal generating unit, an RF amplifier unit, a radiating element, a temperature sensor, and a control unit. The RF signal generating unit oscillates an RF signal. The RF amplifier unit amplifies the RF signal and outputs RF energy. The radiating element radiates the RF energy into the cavity. The temperature sensor is disposed near the RF amplifier unit. The control unit controls the RF amplifier unit to adjust the output of RF energy in accordance with the temperature detected by the temperature sensor and a plurality of threshold levels. This aspect can improve the reliability of the device.

Description

[Technical Field]

[0001] The present disclosure relates to improving the reliability of RF energy emitting devices. [Background technology]

[0002] Conventionally, RF (Radio Frequency) energy radiating devices such as microwave ovens detect reflected wave power, adjust output power according to the magnitude of the reflected wave power, and stop output when the magnitude of the reflected wave power exceeds a predetermined value. In this way, conventional RF energy radiating devices protect themselves (see, for example, Patent Document 1). Patent Document 2 discloses a technology for improving device protection by detecting high-frequency current in addition to detecting reflected wave power.

[0003] 7 shows a conventional RF energy radiating device described in Patent Document 1. As shown in FIG. 7, the conventional RF energy radiating device includes a magnetron 1, a control unit 6, and a detection unit 5.

[0004] A control unit 6 controls a driving unit 7. When the driving unit 7 supplies power to the magnetron 1, the magnetron 1 generates microwaves. A waveguide 2 transmits the microwaves to a power supply unit 4. The power supply unit 4 radiates the microwaves into a cavity 3.

[0005] The detector 5 detects the reflected wave power returning from the cavity 3 to the waveguide 2 via the power feeder 4. The controller 6 controls the driver 7 based on the reflected wave power detected by the detector 5. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 4-245191 [Patent Document 2] Japanese Patent Application Publication No. 2-087929 Summary of the Invention

[0007] In conventional RF energy radiating devices, 30% to 50% of the consumed energy is released as heat, depending on the energy efficiency of the semiconductor amplifier. This energy efficiency varies depending on the load and ambient temperature, and the amount of heat released also changes. The relationship between heat generation and efficiency is a major issue when using semiconductor amplifiers. Terminations that receive reflected power absorb the reflected power and generate heat. For this reason, simply detecting reflected power and high-frequency current does not necessarily provide effective protection for the device.

[0008] The present disclosure is intended to solve the above-mentioned conventional problems, and has an object to provide a highly reliable RF energy radiating device.

[0009] An RF energy radiating device according to one aspect of the present disclosure includes a cavity for placing an object to be heated, an RF signal generating unit, an RF amplifier unit, a radiating element, a temperature sensor, and a control unit. The RF signal generating unit generates an RF signal. The RF amplifier unit amplifies the RF signal and outputs RF energy. The radiating element radiates the RF energy into the cavity. The temperature sensor is disposed near the RF amplifier unit. The control unit controls the RF amplifier unit to adjust the output of RF energy in accordance with the temperature detected by the temperature sensor and a plurality of threshold levels.

[0010] The RF energy radiating device of this embodiment can adjust the RF energy by monitoring the temperature of the heat-generating component, and can efficiently radiate the RF energy to the heating target. Furthermore, by monitoring the temperature of the heat-generating component, the RF energy radiating device of this embodiment can detect the occurrence of a mounting defect and instantly stop the device. As a result, the reliability of the device can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a configuration of an RF energy radiating device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing a configuration of a power amplifier according to an embodiment. [Figure 3] FIG. 3 is a diagram showing an operation sequence in the RF energy radiating device according to the embodiment. [Figure 4] FIG. 4 is a characteristic diagram showing two temperature rise lines of an object to be heated according to the embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing one mounting structure of a temperature sensor. [Figure 6] FIG. 6 is a cross-sectional view showing another mounting structure of the temperature sensor. [Figure 7] FIG. 7 is a block diagram showing the configuration of a conventional RF energy radiating device. DETAILED DESCRIPTION OF THE INVENTION

[0012] A first aspect of the present disclosure provides an RF energy radiating device including a cavity for placing an object to be heated, an RF signal generating unit, an RF amplifier unit, a radiating element, a temperature sensor, and a control unit. The RF signal generating unit generates an RF signal. The RF amplifier unit amplifies the RF signal and outputs RF energy. The radiating element radiates the RF energy into the cavity. The temperature sensor is disposed near the RF amplifier unit. The control unit controls the RF amplifier unit to adjust the output of RF energy in accordance with the temperature detected by the temperature sensor and a plurality of threshold levels.

[0013] In the RF energy radiation device of the second aspect of the present disclosure, in addition to the first aspect, when the temperature detected by the temperature sensor exceeds one of a plurality of threshold levels, the control unit controls the RF amplification unit to adjust the output value of the RF energy according to the temperature exceeding the one threshold level.

[0014] In the RF energy radiation device of the third aspect of the present disclosure, in addition to the second aspect, when the temperature detected by the temperature sensor exceeds another threshold level higher than the one threshold level, the control unit controls the RF amplification unit to reduce the output value of the RF energy.

[0015] In the RF energy radiating device according to the fourth aspect of the present disclosure, in addition to the third aspect, the other threshold level varies depending on the rate of rise of the temperature detected by the temperature sensor.

[0016] In the RF energy radiating device according to the fifth aspect of the present disclosure, in addition to the second aspect, when the temperature detected by the temperature sensor exceeds another threshold level higher than the one threshold level, the control unit stops the RF signal generating unit.

[0017] In a sixth aspect of the RF energy radiating device of the present disclosure, in addition to the first aspect, the plurality of threshold levels include a first threshold level, a second threshold level higher than the first threshold level, and a third threshold level higher than the second threshold level. When the temperature detected by the temperature sensor exceeds the first threshold level, the control unit controls the RF amplifier unit to adjust the output of RF energy according to the temperature exceeding the first threshold level. When the temperature detected by the temperature sensor exceeds the second threshold level, the control unit controls the RF amplifier unit to reduce the output of RF energy. When the temperature detected by the temperature sensor exceeds the third threshold level, the control unit stops the RF signal generating unit.

[0018] In the RF energy emitting device according to a seventh aspect of the present disclosure, in addition to the sixth aspect, the second threshold level varies depending on the rate of rise of the temperature detected by the temperature sensor.

[0019] In an RF energy radiating device according to an eighth aspect of the present disclosure, in addition to the first aspect, a semiconductor element including an RF amplifier is disposed on a substrate such that a bottom of the semiconductor element is in contact with a base plate, and a temperature sensor is disposed on a surface of the substrate opposite to the surface on which the semiconductor element is disposed.

[0020] In a ninth aspect of the present disclosure, in addition to the first aspect, a semiconductor element including an RF amplifier is disposed on a substrate so that a bottom of the semiconductor element is in contact with a base plate, and a temperature sensor is disposed on the same surface of the substrate as the semiconductor element.

[0021] Hereinafter, an RF energy radiating device 100 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0022] Fig. 1 is a block diagram showing the configuration of RF energy radiating device 100. Fig. 2 is a block diagram showing the configuration of power amplifier 102a. Power amplifiers 102a and 102b have the same configuration. Therefore, only power amplifier 102a will be described in detail, and a detailed description of power amplifier 102b will be omitted.

[0023] As shown in FIG. 1, RF energy radiating device 100 includes oscillators 101a and 101b, power amplifiers 102a and 102b, detectors 103a and 103b, circulators 104a and 104b, terminators 105a and 105b, radiating elements 107a and 107b, and a cavity 108.

[0024] Oscillators 101a and 101b oscillate RF signals. Power amplifiers 102a and 102b amplify the RF signals oscillated by oscillators 101a and 101b, respectively, to output RF power. Detectors 103a and 103b detect RF power transmitted from RF energy radiating device 100 toward radiating elements 107a and 107b, and RF power transmitted from radiating elements 107a and 107b toward RF energy radiating device 100.

[0025] Oscillators 101a and 101b correspond to RF signal generating units. Power amplifiers 102a, 102b corresponds to an RF amplifier, and detectors 103a and 103b correspond to an RF power detector.

[0026] Hereinafter, the RF power transmitted from the RF energy radiating device 100 towards the radiating elements 107a and 107b will be referred to as a traveling wave, and the RF power transmitted from the radiating elements 107a and 107b towards the RF energy radiating device 100 will be referred to as a reflected wave.

[0027] Circulator 104a transmits the traveling wave from oscillator 101a to radiating element 107a and transmits the reflected wave from radiating element 107a to terminator 105a. Similarly, circulator 104b transmits the traveling wave from oscillator 101b to radiating element 107b and transmits the reflected wave from radiating element 107b to terminator 105b.

[0028] Terminators 105a and 105b have impedances that act as loads for the waves reflected from circulators 104a and 104b, respectively.

[0029] Circulators 104a and 104b and terminators 105a and 105b protect oscillators 101a and 101b from reflected waves generated in response to load fluctuations of an object to be heated (e.g., food) placed in cavity 108. Radiating elements 107a and 107b radiate RF energy into cavity 108.

[0030] The RF energy emitting device 100 further comprises a temperature sensor 106 a , a temperature sensor 106 b , a temperature sensor 106 c , a temperature sensor 106 d , a microprocessor 109 , and a protection circuit 110 .

[0031] The temperature sensors 106a to 106d are disposed near the power amplifiers 102a and 102b and the terminators 105a and 105b, respectively. The microprocessor 109 is a control unit that controls the RF energy radiating device 100 in accordance with the temperatures detected by the temperature sensors 106a to 106d. The protection circuit 110 operates to protect the RF energy radiating device 100 when the temperatures detected by the temperature sensors 106a to 106d exceed a predetermined value.

[0032] As shown in FIG. 2, the power amplifier 102a (102b) includes a variable attenuator 301, a small signal amplifier 302, and a large signal amplifier 303.

[0033] Variable attenuator 301 receives the RF signal from oscillator 101a and adjusts the amount of attenuation for the RF signal. Small signal amplifier 302 amplifies the signal output by variable attenuator 301 to a certain extent. Large signal amplifier 303 amplifies the signal output by small signal amplifier 302 to a desired RF energy output value.

[0034] The operation and function of the RF energy radiating device 100 configured as above will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram showing the operation sequence of the RF energy radiating device 100. Fig. 4 is a characteristic diagram showing two temperature rise lines of the object to be heated in this embodiment.

[0035] The microprocessor 109 controls the oscillators 101a and 101b to generate RF signals at any frequency. The microprocessor 109 controls the power amplifiers 102a and 102b to adjust the RF energy output to a target value. The RF energy output is adjusted to the initial target value by adjusting the attenuation of the variable attenuator 301.

[0036] For traveling waves, the microprocessor 109 adjusts the attenuation of the variable attenuator 301 in response to the power values ​​detected by the detectors 103a and 103b so that the amount of RF energy remains stable even during operation.

[0037] For reflected waves, At least one of the temperatures detected by the temperature sensors 106a and 106b exceeds the first threshold level, the microprocessor 109 controls the power amplifiers 102a, 102b to reduce the output of RF energy to reduce the amount of heat radiated from the heat-generating component corresponding to the temperature exceeding the first threshold level.

[0038] If the power value detected by the detectors 103a and 103b exceeds the allowable level, the protection circuit 110 uses hardware to instantly shut down the RF energy radiating device 100 to protect the RF energy radiating device 100. The protection circuit 110 reports to the microprocessor 109 that the RF energy radiating device 100 has been shut down.

[0039] Termination devices 105a and 105b are heat-generating components that receive reflected waves and generate heat, resulting in a large temperature rise in termination devices 105a and 105b.

[0040] The efficiency of the large signal amplifier 303 decreases due to changes in the load caused by changes in the physical properties of the object to be heated during heating and an increase in the environmental temperature inside the RF energy radiating device 100. This increases the amount of heat generated by the large signal amplifier 303, and the temperatures detected by the temperature sensors 106a and 106b increase.

[0041] 3. The small signal amplifier 302 has a small output power and therefore a small temperature rise due to heat generation. Therefore, the temperature rise of the power amplifiers 102a and 102b is mostly caused by the large signal amplifier 303.

[0042] The microprocessor 109 detects the temperatures detected by the temperature sensors 106a and 106b. At least one of When the temperature exceeds the first threshold level, the attenuation D (dB) of the variable attenuator 301 is finely controlled by software control so as to reduce the output value of RF energy in order to reduce the amount of heat radiated from the heat-generating component corresponding to the exceeded temperature. For example, the attenuation D can be calculated using the thermal resistance of a semiconductor as shown in equation (1). This makes it possible to prevent the temperature of the power amplifiers 102a and 102b from rising.

[0043] D=10×log 10 P det -10×log 10 (P det -P down ) (1) P det (W): Power value of the traveling wave P down (W): (Detection temperature (℃) - 85 (℃)) × 1 / Z Z (℃ / W): Thermal resistance of semiconductor between junction and case If the environmental temperature increases significantly and exceeds a second threshold level, the microprocessor 109 controls the variable attenuator 301 to significantly reduce the output value of RF energy in order to significantly reduce the temperature.

[0044] 4 shows that the second threshold level varies depending on the rate of rise of the temperature detected by the temperature sensors 106a to 106d. As shown in Fig. 4, when the rate of rise of the temperature is fast, the temperature rise value during one cycle of software control is large.

[0045] Therefore, if the rate of temperature rise is fast, the second threshold level is set lower than if the rate of temperature rise is slow, which makes it possible to reduce the RF energy output value before the temperature becomes too high during one cycle of software control.

[0046] The second threshold level is automatically set to a level that can avoid the device from being stopped by hardware, taking into consideration the rate of increase in the temperature detected by the temperature sensors 106a to 106d and the response time (time lag) when the hardware stops the output of RF energy.

[0047] If a mounting defect such as a solder crack occurs and the temperature rises sharply and exceeds the third threshold level, the protection circuit 110 instantly shuts down the RF energy radiating device 100 using hardware to protect the RF energy radiating device 100.

[0048] As described above, in this embodiment, temperature sensors 106a to 106d are disposed near power amplifiers 102a and 102b and terminators 105a and 105b, respectively. By monitoring the temperatures of these heat-generating components and controlling the RF energy output value, it is possible to suppress temperature increases in power amplifiers 102a and 102b and terminators 105a and 105b. This makes it possible to extend the useful life of the device.

[0049] FIG. 5 is a cross-sectional view showing one mounting structure of the temperature sensor 106a.

[0050] Here, the mounting structure of temperature sensor 106a will be described. The mounting structures of temperature sensors 106b to 106d are the same as that of temperature sensor 106a, so the description thereof will be omitted.

[0051] 5, in this mounting structure, semiconductor element 202 including large signal amplifier 303 is placed on substrate 201 so that the bottom of semiconductor element 202 is in contact with base plate 203. Temperature sensor 106a is placed on the surface of substrate 201 opposite to the surface on which semiconductor element 202 is placed.

[0052] Temperature sensor 106a is placed on the solder surface of substrate 201 and is in contact with base plate 203 made of a material with high thermal conductivity such as copper or aluminum. In other words, temperature sensor 106a is placed at a location with low thermal resistance between temperature sensor 106a and the bottom, which is the heat-generating part, of semiconductor element 202.

[0053] This mounting structure can detect temperatures close to the actual temperatures of heat-generating components. Because the thermal resistance is small, it is easy to correct the detected temperature. As a result, it is possible to detect temperatures with high accuracy and good response.

[0054] 6 is a cross-sectional view showing another mounting structure of the temperature sensor 106a. As shown in FIG. 6, in this mounting structure, As with the mounting structure in Figure 5, The semiconductor element 202 including the large signal amplifier 303 is placed on the substrate 201 so that the bottom of the semiconductor element 202 is in contact with the base plate 203. The temperature sensor 106a is Unlike the mounting structure in Figure 5, The semiconductor element 202 is disposed on the same surface of the substrate 201 as the semiconductor element 202. A through hole 204 is provided in the substrate 201 near the semiconductor element 202.

[0055] According to this mounting structure, it is possible to detect a temperature close to the actual temperature of the heat-generating component, similar to the mounting structure of Fig. 5. This allows the RF energy radiating device 100 to be controlled with high precision. [Industrial Applicability]

[0056] The RF energy radiating device according to the present disclosure is applicable to a defroster, a heat cooker, a dryer, and the like. [Explanation of symbols]

[0057] 100 RF energy radiating devices 101a, 101b oscillators 102a, 102b Power amplifier 103a, 103b detectors 104a, 104b Circulator 105a, 105b terminator 106a, 106b, 106c, 106d temperature sensors 107a, 107b Radiating elements 108 Cavity 109 Microprocessors 110 Protection circuit 201 Substrate 202 Semiconductor elements 203 Base Plate 204 Through hole 301 Variable Attenuator 302 Small Signal Amplifier 303 Large Signal Amplifier

Claims

1. a cavity configured to receive an object to be heated; an RF signal generator configured to oscillate an RF signal; an RF amplifier configured to amplify the RF signal and output RF energy; a radiating element configured to radiate the RF energy into the cavity; a detector for detecting power transmitted from the RF amplifier unit to the radiating element; a temperature sensor disposed near the RF amplifier; a control unit configured to control the RF amplifier unit to adjust the output value of the RF energy in response to the power value detected by the detector, the temperature detected by the temperature sensor, and a plurality of threshold levels; Equipped with the control unit adjusts the output value of the RF energy based on the power value detected by the detector and the temperature detected by the temperature sensor by software control when the temperature detected by the temperature sensor exceeds the lowest threshold level of the plurality of threshold levels, thereby reducing the output value of the RF energy, and stops the output of the RF energy when the temperature detected by the temperature sensor exceeds the highest threshold level of the plurality of threshold levels. RF energy emitting devices.

2. a cavity configured to receive an object to be heated; an RF signal generator configured to oscillate an RF signal; an RF amplifier configured to amplify the RF signal and output RF energy; a radiating element configured to radiate the RF energy into the cavity; a temperature sensor disposed near the RF amplifier; a control unit configured to control the RF amplifier unit to adjust an output value of the RF energy in response to a temperature detected by the temperature sensor and a plurality of threshold levels; Equipped with When the temperature detected by the temperature sensor exceeds one of the plurality of threshold levels, the control unit controls the RF element in accordance with the temperature exceeding the one threshold level. controlling the RF amplifier unit to adjust the output value of the energy; When the temperature detected by the temperature sensor exceeds another threshold level that is higher than the one threshold level, the control unit controls the RF amplifier unit to reduce the output value of the RF energy; The RF energy emitting device, wherein the other threshold level varies depending on the rate of increase of the temperature detected by the temperature sensor.

3. 3. The RF energy radiating device of claim 2, wherein the control unit stops the RF signal generating unit when the temperature detected by the temperature sensor exceeds another threshold level that is higher than the one threshold level.

4. the plurality of threshold levels includes a first threshold level, a second threshold level higher than the first threshold level, and a third threshold level higher than the second threshold level; When the temperature detected by the temperature sensor exceeds the first threshold level, the control unit controls the RF amplifier unit to adjust the output of the RF energy according to the temperature exceeding the first threshold level; When the temperature detected by the temperature sensor exceeds the second threshold level, the control unit controls the RF amplifier unit to reduce the output of the RF energy; 2. The RF energy emitting device of claim 1, wherein the control unit stops the RF signal generating unit when the temperature detected by the temperature sensor exceeds the third threshold level.

5. 5. The RF energy emitting device of claim 4, wherein the second threshold level varies depending on the rate of increase of the temperature detected by the temperature sensor.

6. 6. The RF energy radiation device according to claim 1, wherein a semiconductor element including the RF amplification unit is disposed on a substrate such that a bottom of the semiconductor element is in contact with a base plate, and the temperature sensor is disposed on a surface of the substrate opposite to the surface on which the semiconductor element is disposed.

7. 6. The RF energy radiation device according to claim 1, wherein a semiconductor element including the RF amplification unit is placed on a substrate such that a bottom of the semiconductor element is in contact with a base plate, and the temperature sensor is placed on the same surface of the substrate as the semiconductor element.

8. Further comprising a protection circuit, the RF amplifier section has a variable attenuator; the control unit is configured to control the attenuation of the variable attenuator under the software control to adjust the output value of the RF energy; 2. The RF energy emitting device of claim 1, wherein the protection circuit is configured to disable the output of the RF energy by hardware.

Images