JPS5884315A - Output stabilization method and apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Background of the Invention - Even when limited to a particular manufacturer's model, there is considerable variation in cooking times between microwave ovens; the main reason for this variation is the This is due to the difference in the output of the magnetron. These differences are based on the fact that the outputs (power) supplied by the respective power sources are different. The output supplied to the magnetron by a general-purpose power supply design depends on the effective winding ratio of the plate high voltage generator and the effective capacitance of the storage capacitor.It is possible to measure and adjust these components to obtain a reference plate current. The disadvantage is that the processing is very expensive.

Also, the output of the power supply varies considerably as a function of the AC line voltage, which typically fluctuates by as much as 60% in domestic applications. While output variations due to AC line voltage variations are not insurmountable, accurate power supplies are prohibitively expensive. For this reason, most home microwave ovens use relatively inexpensive power supplies, resulting in outputs of will be issued. For example, the magnetron output supplied from the power supply with the AC line voltage (E) stabilized varies from 600 to 750 watts for the same model, with an average of about 670 watts. , significant fluctuations are introduced into the output due to AC line voltage fluctuations.

Variations in microwave cooking times have caused various problems in the microwave cooking industry. For example, manufacturers of packaged foods may not be able to provide accurate cooking guidelines, which can lead to poor cooking results and the risk of losing customers. Moreover, even if the user follows the cooking guidebook faithfully and cooks according to the cooking time specified by the guidebook, the user ends up being dissatisfied with the result of overcooking or undercooking. Furthermore, in the current state of the 1-weight-based cooking method, it is desirable to include a term determined from the predicted output of the magnetron in the microprocessor algorithm for calculating the cooking time.

The variation in cooking time in open microwave ovens is much more serious than in regular gas open ovens or electric open ovens, where the cooking time depends only on the accuracy of the thermostat and there is no need to take AC line voltage fluctuations into account. That's a problem. Furthermore, with the normal Q open, even if there is a discrepancy between the oven temperature and the dial setting, you can correct it by simply adjusting the dial. Users also know how to compensate for cooking times if the oven does not get hot enough.

Users who are unfamiliar with microwave cooking usually do not have such knowledge. This is the current situation because even if the same microwave oven is used, the cooking time will vary due to fluctuations in AC line voltage.

As is clear from the above, it is desired to make the output of oats constant and uniform and to establish a predictable standard cooking time. To resolve the uneven cooking time, consider the AC line voltage YM.

Techniques are known in which the current cooking time is recalculated as a function of the monitored voltage. Certainly this method is 1! Although some improvements have been made in calculating the J filling time as a function of the varying AC line voltage, one 40
It is not possible to correct variations in cooking time due to variations and differences in each component of the microwave oven power supply.

SUMMARY OF THE INVENTION The present invention provides an A G/DC power supply, means for generating a corresponding signal to trap the output of the power supply, and varying the number of AC cycles to be delivered to the power supply over a series of time periods in response to the signal. means (wherein each time period corresponds to a fixed number of AC line cycles, and wherein the AC cycles provided during the predetermined time period are substantially evenly distributed within the time period). be done. It is preferable that the changing means is constituted by a microprocessor. Further, as a changing means, it is preferable to use a switch inserted between the AC line and the power supply. Further, the fixed number is preferably less than 150 cycles. - If more than half of the total AC cycles are supplied during the period, it is preferable to have a substantially even distribution so that no two cycles are removed in succession. Conversely, when supplying less than half of all AC cycles, it is preferable not to remove two consecutive cycles. Absolutely even distribution (uniform distribution) here means that the supply line cycles are staggered in time with respect to the supply to the power supply, and the interval between adjacent cycles is constant. However, a substantially uniform distribution may include switching out certain line cycles and not shifting the cycles supplied to the power supply in time. In particular, the aim is to minimize the aV of consecutive cycles in which the switch is open and the output is not coupled to the power supply. By minimizing the number of consecutive off-cycles, flicker in home lighting can be reduced. It is best to open and close the switch near the zero current cross. This is because in the case of an inductive load, the current passing through the zero point occurs later than the voltage passing the zero point.

Further according to the invention there is provided an ACi/DO power supply, means for generating a signal corresponding to the output of the power supply, and, depending on said signal, to be supplied to the high voltage transformer of the power supply during a period corresponding to a predetermined number of AC cycles. an output comprising: means for determining a number of AC cycles, wherein the output is stabilized at a predetermined level; and means for supplying said number of AC cycles to a high voltage transformer of the power supply in an evenly distributed manner during said period; A stabilizing device is provided. Further, according to the present invention, there is provided a method for stabilizing the output of an AC/DO power supply to a predetermined output, in which a signal corresponding to the output of the power supply is generated, and a predetermined number of AC/DO Determining how many of the line cycles are to be applied to the power supply, and applying the determined number of AC cycles to the power supply so as to be substantially uniformly distributed over the predetermined number of AC line cycle periods. A method is provided comprising the following.

Further, according to the present invention, there is provided a method for stabilizing the output of an AG/DO power supply to a predetermined output level.

A predetermined number of AC cycles are applied to the power supply during a first period corresponding to a fixed number of AC line cycles.

A signal corresponding to the actual output of the power supply is generated, the difference between the predetermined output level and the actual output level is determined, and the number of signals to be supplied to the power supply during the second period is adjusted so that the actual output approaches the predetermined output level. Determine the Ale cycle (where the adjustment amount is a function of the difference, the second period follows the first period, and is equal in length to the first period), and the determined number of AC lines during the second period.
Supply cycle. A method is provided comprising the following.

Further, according to the present invention, a magnetron, a power supply connected to the magnetron, means for generating a signal corresponding to an anode current flowing from the power supply to the magnetron, and means for changing the output supplied from the power supply to the magnetron in accordance with the signal, A microwave opener consisting of:

The generating means may preferably include a resistor inserted between the power source and the ground, and the generating means may further include means for time-averaging the voltage across the resistor.

A typical average time is about 1 second. Preferably, the power to be delivered is recalculated by the microprocessor for each period of equal length.

Further, according to the present invention, there is provided a magnetron and a power source connected to the magnetron.

means for generating a signal corresponding to the anode current flowing from the power supply to the magnetron; and means for adjusting the anode current stepwise closer to a predetermined level in response to the signal (wherein each adjustment period is constant;
A microwave open is provided consisting of a fixed number of AC line cycles). The stepwise adjustment may be a function of the difference between the signal and a predetermined value. In other words, the larger the difference between the signal and the predetermined value, the larger the adjustment amount 2 is made.

Further, according to the present invention, a magnetron, a power source connected to the magnetron, means for generating a signal corresponding to an anode current flowing from the power source to the magnetron, and means for adjusting the anode current to approach a predetermined value in accordance with the signal ( wherein the regulating means comprises means for varying the number of AC cycles delivered to the high voltage transformer of the power supply in a series of time periods, each time period corresponding to a fixed number of AC line cycles.

A microwave open circuit is provided in which the AC cycles supplied during a predetermined period are evenly distributed within the period. Said signal may correspond to an average current flowing through the magnetron, such that if more than half of the total AC cycles for a period of time are supplied to the high voltage transformer, no two consecutive AC line cycles are removed so that substantially It is best to distribute it evenly. In other words, the switch inserted between the line and the high voltage transformer should not be open for two consecutive cycles.

The invention further includes a magnetron having an output coupled to the conductor cavity, a power supply coupled to the magnetron for providing high voltage pulses, means for monitoring an anode current flowing from the power supply to the magnetron, and a series of means for varying the number of pulses supplied from the power source to the magnetron during the period (wherein the group of pulses supplied during each period is evenly distributed within that period); provided.

It was found that the output power of the magnetron is approximately proportional to the anode current. Furthermore, it was confirmed that even if there is a drift in the AC line voltage, the output of the magnetron opener can be stabilized by sampling the anode current or the corresponding voltage and controlling the magnetron duty ratio accordingly. Additionally, microwave ovens with similar designs can have substantially the same output, making it possible to determine the cooking time of food much more accurately than before. In short, by stabilizing the power supply for each type of microwave oven, the output of the oven can be made constant and uniform.

FIG. 1 shows a block diagram of a microwave open circuit embodying the present invention. In response to a pulsed high voltage from power supply 14, magnetron 12 provides pulsed microwave energy to waveguide 18. Microwave energy is preferably coupled to cavity 16 via a rotating radiator 20 that provides a plurality of directional radiation patterns. The microprocessor 10 stabilizes the power supply 14 and controls the average output of the magnetron 12. Specifically, the microprocessor 10 controls the maximum number of high voltage pulses to be supplied to the magnetron 12 during a predetermined period by adjusting the number of AC (alternating current) cycles to be supplied to the power supply 14 for a period of 100 cycles. reduce. The specific configuration of the interconnections between these components shown in FIG. 1 and the remaining components will be described with reference to FIG.

A monitoring resistor RvY with a small resistance value is inserted between the high voltage output of the power supply 14 and the ground to detect a monitoring voltage proportional to the anode current of the magnetron. Connect the voltage Vvi to the integrator 22 and average 7W for an appropriate time. Determining the time average value is important for two reasons. One is that, as mentioned above, the anode current passing through the resistor Rv is pulsed, and therefore the voltage Vv is also pulsed.

The other reason is that the load on the magnetron fluctuates as the radiator rotates 200 times, and as a result, the anode current fluctuates. That's what it means. For this reason.

An integrator 22 averages the voltage to a voltage proportional to the average anode current. The accumulated voltage is supplied to multiplexer 24. At appropriate time intervals, the microprocessor 10 samples the integrated voltage τ and passes it through the multiplexer 24 to A
The signal is converted into a digital signal by the /D converter 26 and input to the microprocessor 100.

Briefly, the integrated voltage V corresponding to the average anode current
If v is greater than the value required to maintain the output at the desired value, microprocessor 10 reduces the number of AC cycles to be applied to power supply 14 during the charging period. Conversely, if the integrated voltage is less than the required value, the number of AC cycles supplied during the next period is increased.

The specific configuration of the needware will be detailed later.

According to the present invention, a device having the above-described configuration has an advantage over a conventional microwave open device in that a constant and uniform output can be obtained.

Here, "constant" means that virtually the same and stable microwave open output can be obtained even if the AC line voltage input varies, and "uniform" means that a microwave open output of a similar design can be obtained. This means that virtually the same output is obtained. Such a constant and uniform output allows the open cooking time to be determined accurately.

The stabilization of the output has a significant effect on microwave ovens that determine cooking time as a function of weight. In detail, when inputting food weight data into the microphone o7" processor 10 and calculating the cooking time according to the algorithm,
It is preferable to include a term obtained from the output of the magnetron in the algorithm.

However, if the output is not precisely known or varies as a function of AC line voltage, the cooking time cannot be accurately calculated. Referring again to FIG. 1, scale 2B generates an analog signal corresponding to the weight of food within microwave cavity 16.

Select this signal and pass it through the multiplexer 24.

The signal is converted into a digital signal by the A/D converter 26 and used as input to the microprocessor 100. The microprocessor 10 accurately calculates the cooking time based on the initial weight of the food and the initial temperature data of the food device entered by the operator's keyboard operation.

FIG. 2 shows an example of the hardware configuration of the block diagram in FIG. 1. Triacs 40 and 42 act as switches to control whether AC line voltage is provided to heater transformer 44 and high voltage transformer 46, respectively. In normal operation, heater triac 40 closes several seconds before high voltage triac 42 and remains open while high voltage triac 42 adjusts the number of AC cycles provided to high voltage transformer 46 every 100 cycle periods. .

As shown, the secondary side of heater transformer 44 is connected to the heater of magnetron 12. The high voltage transformer supply section of the power supply 14 is constructed from a commonly used general voltage doubler circuit. Specifically, capacitor 48 is charged to approximately -2000V during one half cycle of the AC cycle. During the next half cycle, the capacitor's charge is added to the secondary of transformer 460, and a voltage of approximately -4000 Å is applied to the magnetron 12 cathode. This high voltage causes current to flow from the power supply ground line through the monitoring resistor Rvy to the anode of the magnetron. Voltage Vv is therefore directly proportional to the current flowing through the magnetron anode. After investigating the specific configuration of the magnetron, feed structure, and cavity, it was determined that the average anode current could be adjusted to 300 mA for full power operation. Also, 3'0
It has been found that the average (integral) current BEVY for an average current of 0 mA is 2.2 . To do this
The resistance value of v may be selected to be approximately Z6Ω. Furthermore, it has been found that the integrator 22 for time-averaging Vv may be configured with a Re filter having a time constant of about 1 second. Therefore, preferred values for Ri and Gi are IMΩ and 1 μF. The integrator 22 is.

Typically about 0. The pulsed operation curve of the magnetron 12 having a duty ratio of B is smoothed. Furthermore, the integrator 22 compensates for variations in the anode current due to changes in load conditions as the primary radiator rotates. The integrated voltage Vv is coupled to multiplexer 24 and is selected and passed through the multiplexer according to microprocessor control via one peripheral interface 50. . Multiplexer 24 includes scale 2 for use with the weight-based cooking time algorithm.
The analog signal output from 8 is also coupled. Other analog inputs such as temperature globes may also be sampled and passed through multiplexer 28.

For commercial applications, the microprocessor may be controlled by a custom IC and provided with various twin interface functions. The embodiment of FIG. 2 is a general-purpose microprocessor with auxiliary hardware that connects the microprocessor to a microwave oven control panel, sensors, and magnetron controls via interfaces. As the microprocessor 52, MC86502 manufactured by MOS Chikunoroshii Co., Ltd. can be used. As shown in FIG. 2, the microprocessor is connected to a data bus 54 (typically eight wires each connected to pins 26-36 of the MC86502). The microprocessor is also connected to an address bus 56, which typically has 16 wires connected to pins 9'-25 of the MC86502, respectively.

A conventional initialization circuit (INIT) 58 is used only during microprocessor power-up and is connected to input pins 6 and 40 of the microprocessor MC86502. Additionally, a conventional crystal clock (CLOCK generator) 60 is required and is input to pins 37 and 69 of the microprocessor. Lines 62 connect peripheral interfaces 50, 64, program memory (ROM) 66 and data memory (RAM).
Used to supply blocks to 68. Microprocessor 52 functions the same as microprocessor 10 of FIG. 1 (in FIG. 1 the interface is contained within block 10). Program memory 66 is preferably read-only memory and contains operational programs. The task of writing programs to meet the requirements described below will be apparent to those skilled in the art. Microprocessor 52 issues addresses on address bus 56 to retrieve data from program memory 66 and data memory IJ'ba comprised of random-access memory. Write enable and other control signals from microprocessor 52 are sent via control bus 70 to data memory 60 and peripheral interfaces 50, 64.

Via peripheral interfaces 50 and 64, microprocessor 52 reads data from keyboard 30 and tests the status of various sensors and switches.

Displays the results of internal operations and controls the magnetron. The exemplary peripheral interfaces 50 and 64 are MC86522s whose pins 21-40 are connected to the control, timing, interrupt, data bus, and address bus. Peripheral interface 64 serves as an interface to a control panel that includes keyboard 60 and display 74. Keyboard input to the microprocessor is performed in a conventional matrix scanning manner. In particular, the keyboard is arranged with a matrix of contact or capacitive touch switches. For the control panel of FIG. 7, a 4×6 matrix is sufficient. However, even larger matrices often have 1
Of course, it is possible to provide additional functions that are not explained in this book. Output signals sequentially.

It feeds the columns of the matrix, detects and decodes the rows. Specifically, pins 10-17 of the MC86522 are connected to a high current output buffer 80 and an 8 wire 76 that connects to the segment output board door 8. High current output cover sofa 80 (
For example, the output of the 74LS374 is connected to the keyboard through eight amplifiers 90' through eight wires 82-89 as shown.

Lines 82-89 are provided with pulses for sequential column scanning. Connect the low row of the keyboard switch matrix to line 92.
and supplies it to pins 1 to 9 of the 1 peripheral interface 64. The detected data is decrypted.

The microprocessor 52 controls the switches on the keyboard 30.
Determine which switch in the matrix is closed.

Digital display 74 is scanned. That is, each digit is sequentially driven for 1, for example, 2 milliseconds.

The entire display is scanned at a speed that cannot be detected by the naked eye. Drive circuits (in the illustrated example, there are eight circuits, two of which are shown) are connected to lines 82-89. Each drive circuit shown in the figure.

Typically H + 5 Vcc, 1.5 K1117)
It is composed of R1, 1, R2 of OKΩ, and a transistor Q.

Sequential activation of these drive circuits determines how the display is activated.

Data determining which segment of the digit is to be turned on is sent to the display 74 via resistor 106 wires 94-101).
It is given from the output of the segment output port door 8 which is connected to the segment output port 8. MG3482 can be used as a segment output boat. Data/scan pulse time division line 76 and lines (not shown) providing enable control for port 78 and buffer 80 are connected to pins 6 and 4 of peripheral interface 5o, respectively.

Microprocessor 52 controls the output of magnetron 12 via peripheral interface 5°. In particular, the output of one peripheral interface 5o is supplied via line 104 to a storage output buffer 1o6 (comprised of, for example, a 74LS374). Two of the outputs of the buffer 106 are standard optical isolators L/-108.11 (1 (for example M
OC311o). The opto-isolator shorts out the internal resistance on its output side when its output is at a low voltage (logic 0).

In response to a control signal from optical isolator 108.

Triac 40 turns on and energizes heater transformer 44 . Furthermore, the triac 42 is turned on in response to a control signal from the optical isolator 110, energizing the high voltage power supply.

FIG. 6 shows a cooking control method for the magnetron of the microprocessor 52 of FIG. 2. The program in the program memory 66 of the microprocessor is shown in FIG. 6, and its contents are obvious to those skilled in the art. When a command to start the magnetron is issued, the microprocessor 52.

The peripheral interface 50, high current output buffer 106 and opto-isolator 108'9 described above! : Turn on the heater triac 40 via Prior to application of a high voltage, the ACt current is passed through the heater transformer 44 by passing the triac 40 for three seconds or more to heat the cathode. If less than 3 seconds have elapsed since the heater was turned off, no delay is necessary. Then, set the variable count (COUNT) to the specific chi power x 1
Set to a value of 00 (but not over 70). For example, when operating the open circuit with a 50-channel output, the count is set to 50 (0,5×100). Open 10
When selecting to operate with 0 coefficient output, set the maximum initial value of the carantra to 70. Microprocessor 52 then interfaces with peripheral interface 50 . The high voltage supply triac 42 is turned on via the high current output buffer 106 and the optical isolator 110. The triac acts as a switch and supplies the AC line voltage to the high voltage transformer 46 for a set count number of cycles during the first 100 AC cycles. Switching is performed at the zero cross point of the AC current to prevent high current interruption. The output of an ordinary zero-cross detector is fed to a microprocessor 52 to obtain the required timing.

The active pulses or cycles are evenly distributed over the next 100 cycles to reduce line current surges and fluctuations. Specifically, if the desired duty ratio is greater than 50 inches (count greater than 50), only one pulse in the sequence should be skipped (avoid skipping more than one pulse in a row).

If the desired duty ratio is less than 50 pulses, at most one pulse should be activated during the sequence (at most two or more pulses should not be activated in succession). After 1.00 AC cycles have elapsed (after 1.67 seconds), the output of the integrator 22 is sampled, passed through the multiplexer 24, and converted into a digital signal by the A/D converter in order to measure the anode current with the microprocessor. input to peripheral interface 50; The detected anode current is then compared with the anode current set by the operator. For example, as mentioned above,
In the preferred embodiment, a 100-channel output corresponds to an average anode current of 300 mA. Therefore, when selecting 50*output, the set average anode current is 300 mA
half of that, 150 mA. Also, as mentioned above, an average anode current of 300 mA is applied to multiplexer 24.
Corresponds to the average voltage of 2,2■ at 0 input. Therefore, if the input voltage of the multiplexer is 1.1v, then 150
The actual anode current is mA ((1,1/2.2)
X 300. ). If the difference between the actual anode current and the set anode current is greater than 23mA, increase the count to 6.
Only increases and decreases.

Reduce the difference between the two. If the difference is 11-20mA.

Increase/decrease the count by 2 and bring the two closer together. The difference is 4-1
If it is 0mA, increase or decrease the count by 1 to reduce the difference.

If the difference is 3mA or less, leave the count unchanged. Then the magnetron's high t EE'& during the next 100 cycles, give the number of corrected counts in the nox. In short, the number of magnetron pulses to be supplied during the 100 cycle period is appropriately increased or decreased so that the actual anode current becomes equal to the set anode current, and the greater the difference between the two, the greater the adjustment amount. For example, if the average anode current is set to 300mA for 100% output (A
(corresponding to 94 AC cycles out of 100 cycles of the C line voltage), the initial maximum number of 70 high voltage pulses is applied to the magnetron during the first 100 AC cycles, and the difference with the actual anode current is 6 pieces in each subsequent 100 cycle period until 20 or less (74).
Increase the number of rules by 10 each until the difference becomes 10.
The number of pulses is increased by two for every 0 cycle period.

Figures 83 to 8C show the relationship between the AC line voltage and the anode current flowing through the magnetron. In particular, Figure 8a shows the AC line voltage (typically 60 or 50
cycle)'lk is shown.

FIG. 8b is an example of the AC line voltage applied to the high voltage transformer 46. Specifically, the microprocessor 520-controlled interface 50. High current output puffer 10
6. The triac 42 is operated as a switch via an optical isolator 110, removing energization of the high voltage transformer 46 during all but the second and sixth AC line cycles of FIG. 8a. As mentioned above, switching is preferably performed at the zero-crossing point of the current. When the load is highly inductive like a typical open microwave.

The current zero-crossing point is approximately 90° from the voltage zero-crossing point.
I'll be late. Therefore, Fig. 8b shows only an example of selecting pulses to be passed and pulses to be excluded, and Fig. 8c shows the anode current flowing through the magnetron. The duty ratio of the pulses applied to the magnetron is typically in the range of 0.25 to 0.35.

As previously mentioned, the AC line cycles supplied to high voltage transformer 46 during a given time period are uniformly distributed within that time period. Specifically, when supplying more than half of all AC cycles within a predetermined period,
It is preferable that the triac 42 as a switch not remain open for more than two cycles at a time. average 1
It is preferred that the triac 42 as a switch not remain closed for more than two cycles at a time when supplying less than half of the total cycles during the period. In this way, fluctuations and surges in the AC line can be suppressed for a short period of time. For example, the flicker of household lights can be made less noticeable.

As an algorithm for evenly distributing the AC cycles to be supplied during a predetermined period, it is preferable to add the above-mentioned count (OOUN↑) to the contents of the register for each period. If the content (number) of the register is greater than the number of AC cycles within the period, is the triac 42'?
: Turns on during that AC cycle and subtracts the number of cycles during that period from the contents of the register. If the contents of the register are not greater than the number of AC cycles in the period, triac 4
2 is turned off during its AC cycle. 1 as a predetermined period
Although the 00AC line cycle Z is shown as an example, other length periods may be used. In fact, for some applications it may be better to use a shorter period to increase the response speed. At the end of the predetermined period (
This table shows a table obtained when the above-mentioned algorithm is used with a base period of 60 cycles. As shown in the table, the ON cycles are distributed substantially uniformly within the base period. In the table, ``0'' represents an AC line cycle where the triac 42 is open (therefore the high voltage transformer is in the de-energized state D) and @X'' represents the AC line cycle when the triac 42 is closed (therefore the high voltage transformer is in the energized state) Represents AC line cycles.For example, if the count is 36, 66 out of 60 cycles available in the period will be supplied to the high voltage transformer.

They may be equally distributed within a 60 cycle period of -seconds. If we add the count 36 to the register, its contents are less than 60, so the first A
For the C line cycle, the triac 42 (switch) is opened. Next, add the count 36 to the register and make its contents 72. Since 72 is thicker than 60, triac 42 is closed for the second AC line cycle and subtracted from 6172 to make the contents of the register 12. For the sixth AC line cycle, the count 36 is added to the register value 12 to make 48. Because 48 is smaller than 60.

The triac 42 is opened. This process continues for the entire period (in this case 60 AC cycles or 1 second). A new karanthra is then calculated as described in FIG. 6, and processing continues.

FIG. 4, FIG. 5, and FIG. 6 show a front view, a side view, and a top view, respectively, of a microwave opener with a scale 28 that makes the present invention effective. The heating cavity 16 contains food 112 which is introduced through an opening in a door (not shown). Many well-known common components (e.g. door sealing structure) are not shown as they are not relevant to the present invention. From an ordinary magnetron 12, the microwave energy of 2450M) 1z is rotated through a waveguide 181 and then a radiator 2.
0, and the output power of the resistor is preferably such that most of the energy is absorbed directly into the food without being reflected off the cavity walls. In detail: - The radiator 20 is composed of an array of antenna elements 20a'& 2X2, and each element of the antenna is supported on the earthen wall of the microwave open cavity via a conductor extending perpendicularly to the element. It consists of an end-driven bamboo wavelength resonant antenna element. Via parallel plate-like microstrip transmission lines 20CY, each support conductor is coupled to a central junction 20d concentric with the axis of rotation. A cylindrical probe antenna 100 is attached to the structure of the resistor 20 at the joint. Probe antenna 11
0 has a capacitive head and is supported by a plastic bushing 117 located within the waveguide. This bushing allows the probe antenna and resistor to rotate about the axis of the probe antenna. The probe antenna 100 is generated by the microwave energy introduced into the waveguide 18 from the output rope 116 of the magnetron 12.
is excited. The energy travels through a probe antenna 110 that acts as a coaxial conductor and passes through a hole 119 drilled in the earthen wall of the open cavity.

The upper wall of the cavity 16 forms a dome 127, the cone of which extends around the periphery of the wall and is a generally circular concave shape partially surrounding the directional rotation register.

Distributes energy uniformly to the food to be heated.

The dome returns microwave energy reflected from the food to a circular area in the center of the microwave open cavity. Preferably, air for magnetron cooling is sent out from a blower (not shown) and circulated through the cavity to remove steam. It is preferable that the resistor 20 is rotated from the air waveguide 18 through the aperture 121 in the dome wall. register 20
is coupled to the fin 123, which is driven by air to generate rotational force. The fins can be made of plastic lossless material. Other paths may be used to direct air from the blower to the fins. Further, instead of being driven by air, the radiator may be rotated by a motor (not shown). Grease book shield 125 is transparent to microwave energy;
Provide splatter zero isolation for the remainder of the cavity.

The control panel detailed in FIG.
2. A keyboard function that provides input information.

The microprocessor has a display function that displays information that should be communicated to the user. Any number of keyboard switches and displays can be used. A well-known capacitive touch pad switch would be suitable as a keyboard switch. Further, it is preferable that the display digitally display parameters such as time, and at the same time display which switch on the keyboard is selected.

, a scale 2B is installed under the bottom plate 118 of the cavity. The scale 28 includes four vertical support pins 122 that pass through holes 124 formed near the corners of the bottom plate of the cavity 16. Supported by this mechanism, plate 126 rests at a height of approximately 1 inch (2.54 crn) above the corner of the bottom plate of the cavity. Typically, this plate is constructed from a Pyrex glass material that is transparent to microwaves. The microwaves that pass through the glass hit the bottom plate of the cavity, are reflected, and hit the underside of the food. The microwave energy is thus applied to the entire surface of the food. Additionally, the plate also acts as a protection measure for the magnetron in the event that the open is accidentally energized when there is no load in the cavity. When cleaning, use glass
The plate may be removed, but it must be kept in the open position at all times during operation. The weight of the glass plate, food, and utensils is transferred to the scale 28 through the support pin 122.

Microwave energy should be prevented from entering the chamber 128 containing the scale through the four pin holes 124. Therefore, the pin hole 124 is circular and its circumference is shorter than the rod wavelength. Specifically, the hole should be slightly larger than the pin, which is approximately A inch in diameter. In order to improve the weighing accuracy of a scale, it is important to minimize the friction of the pin as it moves up and down the hole. For this purpose, the pins are placed correctly and concentrically in their respective holes, and a material with a low coefficient of friction is used.

Preferably, the pin is made of a microwave transparent material such as ceramic, and the microwave passes through the hole. make it close. If the pin were made of metal, the structure would have a type of coaxial line characteristic in which the large surface is the outer conductor and the pin is the center conductor. Therefore, even if the size of the outer conductor is set below the cutoff, microwave energy will still pass through.

The scale 28 includes four rigid lever arms 136. At one end of each lever arm there is an inverted V-shaped bracket 167, and the arm t has a fulcrum 167 with a knife-like edge.
I support 40. The other end of the arm is attached to the second arm by a semicircular pivot pin 141,
The joint portions of both arms are capable of vertical movement between supporting points at both ends. The lever arms 1360 pairs are arranged parallel to each other, with each pair having a corresponding arm in the other pair. These corresponding arms have V-shaped rungs 14 running at right angles to the lever arms to which they are connected.
6 can be firmly attached. In the illustrated scale 28 embodying the present invention, each arm is approximately 7 inches long and the rungs are approximately 14 inches long and mounted approximately 1 inch from the fulcrum. These dimensions allow the scale to fit snugly within chamber 128, with the pins passing through holes 124 at appropriate locations. Pivot pin 141
A flexible metal piece supported by a set of cantilevers on a block 146 is used as a follower member 144 to suppress the downward movement of the lever arm at the joint. Rod 1. ．． 4B'Y Pivot Attach firmly to the lever arm near the bin joint and in a direction perpendicular to the lever arm. A disk 150 that rests on the driven member 144 is provided at the end of the rod.

As mentioned above, the weight of the plate 126 and anything placed on it is caused by the pin 122y projecting into the cavity through the hole 124 in the bottom wall of the cavity! - The information is conveyed to the collection through. pin 12
2 is attached to a rectangular bracket 152 that suppresses the vertical movement of the pin. A rectangular bracket 152 is rigidly coupled to the inner lower end of the V-shaped crosspiece 146 adjacent each lever arm. Regardless of the distribution of the forces acting between and below the four pins 122, the forces are transmitted in approximately the same ratio through the rungs to the lever/arm on the driven side of the scale.

Rondo 148 transmits force from the lever arm through disk 150 to driven member 144 . The greater the weight and corresponding downward force, the greater the deflection of the flexible follower 144 (the follower acts similar to a spring). The vertical position of the free end of the follower thus represents the weight acting on pin 122. , the free end of the follower member 144 bends downward, and the shade member 157 interrupts a portion of the light beam 154 that would otherwise be incident on the photodetector 1″56.Plate 126
As the upper weight increases, the free end of the follower member 144 bends further downward, making it difficult to cut off the light beam 154 that should be incident on the photodetector 156. The photodetector 156 can be composed of a photo-transistor that outputs an analog voltage in response to incident light. Light source 158 of light beam 154
A good example would be a light bulb as shown in the figure or a light emitting diode. A concave lens may be placed between the light source and the photodetector to focus the light beam into a small area. In this way, the area of the incident light does not change, but the light intensity within the small area becomes variable.

Scale 28 provides weight information to microprocessor 10 (or microprocessor 52 in FIG. 2) of the object within the cavity. The above-described scale 28 has the advantage that it can be installed in a commercially available microwave oven without any particular design changes. Specifically, for a microwave oven housing a scale, the height of the chamber 128 may be approximately 1 inch at the center and about 1 inch at the center and around the periphery. Figure 4, Figure 5,
Figure 6 is not drawn in proportion. Bottom plate 11 of cavity 16
The corners and edges of 8 should be raised to keep the food on plate 126 at a higher temperature than the conductive surface of the bottom plate, which has very low dielectric loss.
I will make it happen. 'The scale has a rectangular structure with a height of about 1 inch and a blank center.

It should fit snugly around the perimeter of chamber 128, which is about 1 inch high. Furthermore, since the scale has a blank structure in the center, it can also be used for microwave openings where food is added from the bottom.

The reference clock for microprocessor 52 is provided by clock 60. The clock 60 may consist of an AC filter connected to the AC power line of 60m (Z) and a zero-cross detector, and supplies the zero-cross output to the microprocessor.

FIG. 7 shows an enlarged view of the control panel 74 comprising the keyboard 30 and display 74.

As mentioned above, the keyboard switch may be a general capacitive touch pad switch. Typically, a 7-f panel interface is connected between the keyboard and the microprocessor. The twin interface may be an ordinary one used in many city microwave ovens. Similarly, the microprocessor and control panel 7
A high voltage drive interface 7A is connected between the two displays and serves as a light indicator. As the touch pad 200 of the keyboard, 0-9, CLOGK, READY
.

TIME, DISHWEIG) JT, THAW, WAR
M.

HEAT, GOOK PROGFIAM, 5TIR, T
IMEF(.

There is a pad marked REDUCED POWER, TIMIli;R. The display includes a digital display section 204 and function indicator lights 20 associated with each touch pad.
There is a digital display 208 associated with the 6 and C00K pRoGRffiu pads.

In operation, touchpads 0-9 are used normally to enter data relating to well-known functions into the microprocessor. For example, when the microwave is open/not in use, the digital display section 204 displays time Y. If the user wishes to change the time, the user presses the number pad corresponding to the desired time. Then, the time will be displayed on the digital display section 204.

When you press the clock, the displayed time enters the microprocessor and becomes a new poem. Another use case is to use the number pad to set and display food cooking times. 5T
When you press ARTv, the displayed time will count down until the ople runs out.

The THAW pad is used to raise food from a frozen temperature of 0"F' to a melted state of 40"F' under magnetronke control via a microprocessor. The WARM function pad is used to control the magnetron through the microprocessor to raise the food from 't'40'F to 657. The HEAT function pad controls the magnetron via a microprocessor to move food from 65"F' to 1607"
Used for heating.

The GOOK PROGRAM function pad is used to control a magnetron via a microprocessor to pass food through a cooking process at temperatures as high as 160"F or higher. In other words, THAW.

The WARM, )IEAT, and C00K inputs represent the initial temperature of the food. Before starting cooking, C00K PFIOG
Select the appropriate E (AM) for the food. To select, touch the appropriate number band and then Go OK
PROGRAM 'Touch Y to perform. The selected program is displayed on the digital display section 208. If you want to cook on a weight basis as detailed later, use REDUCE.
D PO[:Touch R pad and Tl1i:MPH
OLD i operates and lowers the magnetron duty ratio. During normal time-based cooking operation, HEDUCE
By touching the D POWER pad,
The cavalry/column indicator works.

The EADY TIME function pad is used to preprogram the microwave oven to turn on after a certain amount of time.The 5TIRTIMEFt provides an alarm when stirring food or other processing is to be performed.
Used to cut open. The TIMER function is associated with microwave ovens. It is used as a countdown clock that counts down for one hour and issues an alarm when the clock is turned on or off. The 5TART button initiates execution of a predetermined program subroutine that turns on the magnetron. Turn off the magnetron with the sTO'r/RgsET button. Each time the LIGHT button is pressed, the cavity illumination light (not shown) flashes repeatedly.

The programming of the microprocessor for magnetron output stabilization has already been explained.

As mentioned above, the principle of the invention is:

A microwave oven is provided with a scale coupled to its cavity, which provides a special advantage in calculating its cooking time based on the initial weight of the food in the cavity and operator input information regarding the initial temperature of the food. .

As explained in connection with FIGS. 1 and 2, an analog signal corresponding to the initial weight of a food product is sampled by a microprocessor. Among the programming of the microprocessor, the method of calculating the cooking time will be described below. Of course, the microprocessor may perform a variety of functions other than those described herein.

For example, temperature probe monitoring, interlock monitoring, setting time, setting power, etc. can be performed.

The following formula is used for "calculating heating time".

Here, HUS selects heat unit ()leat Unit3
FW is the food weight (Food W
eight).

Di is dish weight, SHD
is the specific heat of tableware.
sh ), OPL is the open output level yv (0v
power level), PLS is output level selection (Power Level 3electi)
on ), OF is the coupling coefficient (Coupling Fac
tor).

In the heating time formula, the first term is the heat unit selection, which is the food 1
BTU"k per bond. It has been found that the amount of heat required per unit weight of food (required heat units) depends on the temperature range over which the food is heated and chemical and/or physical changes occur in the food. This term of the equation can be determined by very simple keyboard input by the operator.

Referring again to FIG. 7, the operator selects the THAW corresponding to frozen food (0"F) to indicate the initial temperature of the food.
, WARM, which corresponds to cold food (40″F), such as taken out of the refrigerator, or jEATV, which corresponds to room temperature food (65″F). If you touch two or more of these pads, a separate cycle will start for each function,
The calculation of the heating time equation is done separately for each cycle. T) j If it is AW Psile, it is 100 BTU
/Put Bond into the equation. 25B for WARM cycle
Putting TU/bond into the equation, if HEAT cycle, then 10
Enter 0 BTU/vod into the formula, and if it is a GOOK cycle, select it with the touch pad and display it on the GOOK PROGRAM touch pad. According to GOOK PROGRAM.

Enter 25-250 BTU/bond into the equation.

The heating time at the maximum output level can be determined by IJ, but H
If the EDUCED POWRE setting is made,
Extend the time required to create a special factor.

In other words, for more detailed cooking.

Because of cooking, the BTU value itself is the same, but it is distributed over a longer period of time.

The second term of the heating time equation is [food weight (FW) + tableware weight (DW) (tableware specific heat 5HD)]. It is obvious that food weight is present in the formula. Multiplying this unit (pounds) by the thermopotential selection (,,BTU/pound) gives the BTU for the numerator of the equation, which can be divided by the denominator unit (BTU/minute) to get the fraction in the desired units. is obtained. By including (tableware weight) x (food specific heat) in the equation, it is possible to compensate for a portion of the heat transferred to the food by conduction out of the heat supplied to the food. In other words, there is a loss that is transmitted to each tableware, so it is necessary to apply more heat to the food than is theoretically required.For the convenience of the user, when calculating the heating time formula, the temperature of one tableware is Regarding the WARM and HEAT cycles, which increase due to conduction as the temperature of food increases, the specific heat of one tableware is assumed to be a constant 0.2.THAW and GO
In the OK cycle, the specific heat of one tableware is set to zero, and the product of specific heat and tableware weight is excluded from equation 1. In the case of THAW, the size of 1 tableware transfer 5 BTU is smaller than the BTU consumed to melt frozen food, and in the case of GOOK, 1
Starting at 60"F', the temperature rises very little. A more accurate representation of heat loss in food (and therefore considering the addition of heat needed to deliver it to the food).

Although it is necessary to take into account the specific heat of the food and the heat rise of the gas in the cavity, experience has shown that it is sufficient to use the above heating formula in the above position. 1 in action
When the indicator light on the dish weight pad turns on, this indicates that the dish weight has been entered into the microprocessor. Therefore, when starting a new cooking process using new tableware, touch the tableware weight pad to turn off the indicator light once. This erases the tableware weight before the microprocessor,
Set the scale to zero. Next, to enter the weight of the tableware into the microprocessor, 1. If the weight is known, set the weight using the number pad; if not, 5. Place only the tableware in the open without any food and weigh it on the scale. When you touch the tableware weight pad again, the indicator light turns on, indicating that the new tableware weight has been entered into the microprocessor. It is preferable that the analog voltage output from the photodetector 156 is set to be approximately linear with the weight placed on the scale. That is,
By using a linear A/D converter, the microprocessor can directly sample the bond weight. If the analog voltage is not near the weight and IJ, for example if it is inversely proportional as in the embodiment of FIG. 4, this can be compensated for by providing conventional means such as a look-amp table on the microprocessor side. To improve weight accuracy, a microprocessor can take multiple weight samples during weighing, remove one that is too heavy and one that is too light, and take the average of the remaining samples. The weight of the food is obtained by weighing it just before pressing the 5TART button, and subtracting the weight of the tableware after zero adjustment.

The first term in the denominator of the heating time equation is the open output level (O
PL). With the traditional weight-based cooking time method, there is considerable variation in output from opening to opening.
The output could only be roughly estimated. moreover,
, the output of the two open circuits also varies as a function of the AC line voltage. In short, the calculated cooking time contained a considerable amount of error because the output could not be determined with high accuracy. One principle of the present invention, which is to stabilize the power supplied to the magnetron, allows the open output level (OPL) to be accurately determined. This is because 1. For example, when outputting 100 channels, the current flowing to the anode is a constant value QQm
A, which is 725 output, or 41.2
Corresponds to 8TU/min.

The second term in the denominator of the heating time equation is the output level selection (PLS).
). TEM with REDUCED POWER Bud
If P HOLD (temperature hold) is not specified.

In the formula for heating time, enter 1a- as the value of PLS.

REDUCED POWfi: TEMP on R pad
If HOLD is instructed, enter 0.3 plus 0.04 per bond of food in the % formula PLS. For example, if the food is 1 ton Wit, the magnetron is operated at full output of 64 Hz. If it is 2 pounds, the output will be 68 inches. This can be achieved by lowering the duty ratio of the magnetron.

It has long been known that some foods taste better when cooked at low temperatures rather than at high temperatures.

For some other foods, it is better to reduce the microwave energy output by Y. For this reason, most microwave ovens are equipped with an output level selection function. Through the development of weight-based cooking methods.

It has been found that it is very important to determine the total number of TUs required for the food and to provide it to the food, and the rate of supply of microenergy is not so important.

Tl1i: One MD HOLD function is sufficient if it is a setting function for only one reduction output level (which is a function of the weight of food). Generally, the reduced power for TEMD HOLD is
This provides an excellent effect when used for foods that have a large volume and where microwave energy is almost attenuated before it penetrates into the center. To ensure uniform heating and cooking, it is necessary to make sure that the heat from the outside of the food reaches the center, and to lengthen the cooking time accordingly. I have found that for light foods, it is very convenient to keep the food at a temperature that can be achieved at full power of about 64 inches. In the PLS formula, the term added by 4% for each bond is a compensation term for large foods. If the food is thick, its surface area will not be large and the heat loss will be large, so it is necessary to compensate for this loss in order to maintain the temperature. The assumption that food surface area or volume is related to weight has been empirically confirmed.

The last term in the heating time equation is the coupling factor (OF). Not all of the output from the magnetron is given to the food; some of it is absorbed by walls, waveguides, plates, etc., resulting in loss. The proportion of total energy that is converted into heat in food (ch) depends on the food's surface area and its absorption rate.

For example, if one potato requires 4 minutes to cook, it will take less than 8 minutes to cook two potatoes, rather than twice as long. This is because as the food load increases, the proportion of total energy absorbed by food increases.

The proportion of energy distributed to food is approximately the following formula: % where the constant can be seen as an open loss as a function of weight. Assign 0.1 to the constant. Therefore, if the food weight is 0.1 bond, the bonding coefficient is 1. The heating time is extended twice as long as without the coupling coefficient. However, for 1 bond food, the heating time is 1.1
It just doubles.

In FIG. 1, block 1 represents a microprocessor.
The graph shows that as the weight increases, the energy coupling to the food improves, so the heating time per unit of weight decreases.

[Brief explanation of drawings]

FIG. 1 is a block/schematic diagram of a microwave oven showing an embodiment of the present invention. FIG. 2 is a hardware configuration diagram of the block diagram in FIG. 1. FIG. 6 is a flowchart of a microprocessor program according to the present invention. Figure 4 is a partially cutaway diagram of the microwave opener with scale. Fig. 5 is a view taken along line 5-5 in Fig. 4, and Fig. 6 is a partially cutaway view. FIG. 4 is a top view. FIG. 7 is a diagram of the control panel of FIG. 4. FIG. 8 is a diagram showing the relationship between AC line cycle, supply cycle and anode current. (Outside 4ri) F/G, Bc

Claims (1)

[Claims] 11) A method for stabilizing the output of an AO/DO power supply to a predetermined output. Generate a signal corresponding to the output of the power supply. Determine how many of a predetermined number of AC line Φ cycles should be applied to the power supply in order to bring the output closer to a predetermined output. A determined number of AC cycles is applied to the power supply substantially evenly distributed over a predetermined number of AC line cycle periods. A method consisting of: (2) A method for regulating the output of an AC/DC power supply to a predetermined output level, the method comprising: providing a predetermined number of AC cycles to the power supply during a first period corresponding to a fixed number of AC line cycles; Generates a signal corresponding to the actual output of the power supply. Find the difference between the specified output level and the actual output level. In order to adjust the actual output close to the predetermined output level, calculate the number of AC cycles that should be supplied to the power supply during the second period (here, the amount of adjustment is a function of the difference). , and the length is equal to the first period). The determined number of AC line cycles is provided during the second period. A method consisting of: (3) A method for stabilizing the output of a microwave open circuit to a reference output level. A signal corresponding to the time average value of the anode current flowing through the magnetron from the high voltage power supply is generated. The difference between the calculated actual output level and the reference output level is periodically determined (here, the actual output level can be obtained from the above signal). Based on the difference, determine the number of AC line cycles to be applied to the power supply in the next period of the series (where each period is a fixed number of AC line cycles long). During the next period, the determined number of cycles is uniformly distributed and supplied. A method consisting of: +41 AC/Do power supply. and means for generating a signal corresponding to the output of the power supply. means for varying the number of AC cycles to be applied to the power supply over a series of time periods in response to a signal, where each period corresponds to a fixed number of AC line cycles; substantially uniformly distributed within the period). Output stabilization device consisting of: (51) In the device according to claim 4, the changing means is constituted by a microprocessor. (6) In the device according to claim 4, the changing means further includes a (7) In the device according to claim 4. The fixed number is less than 150 cycles. (8) In the device according to claim 41. - During the period , when supplying more than half of the total AC cycles, ensure that no two consecutive cycles are removed to provide substantially uniform distribution. +91 Corresponds to Ale/DO power supply and power supply output. and means for determining, in response to said signal, the number of AC cycles to be supplied to the high voltage transformer of the power supply during a period corresponding to a predetermined number of AC cycles, wherein the output is stabilized at a predetermined level. and means for supplying said number of AC cycles to a high voltage transformer of a power supply in an evenly distributed manner during said period. In the device according to claim 10, the determining means comprises a microprocessor.
The supply means shall have a switch inserted between the AC line and the high voltage transformer. fiJ In the device according to claim 9,
The above period shall be shorter than 150 cycles. (Ill. In the device according to claim 9. When supplying less than half of the total AC cycles, the above-mentioned equal distribution is performed by ensuring that two cycles are not excluded in succession. I. A magnetron. A power supply connected to the magnetron. Means for generating a signal corresponding to the anode current flowing from the power supply to the magnetron. Means for changing the output supplied from the power supply to the magnetron in accordance with the signal. wave open.Q51 In the order/as set forth in claim 14, the generating means has a resistor inserted between the power supply and the ground.ae In the open as claimed in claim 15, the generating means further comprises: It has a means for time-averaging the voltage across the J resistance. aη In the oven according to claim 14, the changing means has a microprocessor. (1) In the oven according to claim 17 , the microprocessor recalculates the output to be provided at each period of equal length. A magnetron. A power supply connected to the magnetron. Means for generating a signal corresponding to the anode current flowing from the power supply to the magnetron; Means for adjusting the anode current stepwise closer to a predetermined level in response to the signal (wherein each adjustment period is constant;
(to accommodate a fixed number of AC line cycles). Microwave oven consisting of. In the open statement in claim 19,
The generation means is a resistor inserted between the power supply and ground. C! υ In the open matter according to claim 19, the adjusting means includes a microprocessor. 4. In the oven according to claim 19, the one-step adjustment is a function of the difference between the signal and a predetermined value. Otsu 1. In the open circuit described in claim 19, the fixed number is less than 150 cycles. (24) Magnetron. Power supply connected to the magnetron. Means for generating a signal corresponding to the anode current flowing from the power supply to the magnetron, and means for adjusting the anode current to approach a predetermined value in accordance with the signal/signal (herein, the adjustment means means for varying the number of AC cycles supplied to the high voltage transformer, each period corresponding to a fixed number of AC line cycles, the AC cycles supplied during a given period being evenly distributed within the period; ). Consists of microwave open. (2) In the open state described in claim 24, the signal corresponds to the average current flowing through the magnetron. (C) In the open state described in claim 24, the period . It should be short. In the open statement set forth in claim 24,
When supplying more than half of the total AC cycles for a period to a high voltage transformer, no two consecutive AC line cycles are removed to provide substantially equal distribution. (c) A magnetron having an output coupled to a conductive cavity. A power supply that couples to the magnetron and provides high voltage pulses. means for monitoring the anode current flowing from the power supply to the magnetron, and means for responding to the monitoring means and changing the number of pulses supplied from the power supply to the magnetron in a series of periods (herein,
The pulses delivered during each period are evenly distributed within that period), consisting of a microwave open circuit.