CA1220837A - Heating appliance - Google Patents

Abstract

ABSTRACT
TITLE: Heating appliance This invention relates to safety means for such heating appliances having a digital control section (3) as electric ovens, microwave ovens, and composite ovens which comprise the two preceding types, wherein the completion of setting of a timer (5a, 5b) or the like is judged by the passage of a given time, and the com-pletion of preparation for preheating is reported, while the sequence is advanced to make the start of heating possible. Further, the placement of an object to be heated (15) in a heating chamber (11) is judged by the opening and closing movement of a door (2), and a stand-by report is made to make the start of heating possible.
Further, in a heating appliance which requires preheating, the preheating completion time is estimated and reported to facilitate the preheating operation.

Description

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SPECIFICATION

TITLE: Heating Appliance TECHNICAL FIELD
This invantion relates to safety means for such heating appliances having a digital control section as electric ovens! microwave ovens, and composite ovens which comprise the two preceding types~ wherein the preheating completion time is estimated and reported, the completion of preparation for cooking is detected by the opening and closing of the door, the time for pushing the start switch is reported, and the completion of preparation is reported upon ascertainment of the completion of timer setting.

B~CKGROUND ART
The recent development of semiconductor technology is remarkable, and incorporation of electronic circuits in control systems is increasing rapidly. With the advent of stored logic type controllers represented by the microcomputer, digitali~ation of control systems is also increasing rapidly.
In the field of heating appliances also, the wave of such digitalization has changed the arrangement of control systems and the configuration of operating panels to a large extent. New functions which would be .

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- 2 -impossible to attain with conventional discrete circuits have been added one aEter another.
However, such digitalization of opera-ting ~anels and adaptation of heati~g appliances for mul-tifunction can complicate the operation of the appliance, resulting in an increasing tendency for the user to e~perience troubles; she fails to fully utilize the "helpful"
functions or erroneously operates the appliance, leading to unsatisfactory heating. Even a failure of part of the circuitry can cause the control system to run away, contrary to the user's intention.
Accordingly, there has been a desire for a heating appliance which will never start heating until the user has set desired data on heating, will report to the user the acceptance of the effective heating data by the control system to thereby make the operation readily understandable, and is capable of preventing the control system from running away even in the event of a failure.
As for an error often found particularly in the composite oven, the user forgets to do the idle heating, which is called preheating, (i.e., heating with no load put in the heating chamber) and consequentl~ fails in cooking or by mistake she dose the idle heating for a cooking mode which forbids it. The number of such errors is increasing.
The manner of operating the heating appLiance largely depends on differences in -the type of heat source and in r- ~ -. --- -, . . ~.......... _ 7~ , .

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- 3 -the method of heating food.
First, reference will be given -to heating appliances equipped with an electric heater or gas burner as a heat source, such as an oven`(hot oven) and grill. These heat sources heat food externally. Further, these heating methods can be roughly classified into two types by the heating mechanism, as follows.
One type ls oven heating wherein food is baked in a heated atmosphere. This is a heating method wherein food ls baked in a high temperature atmosphere with the radiant heat from the heat source being prevented from reaching the food. In this case, it is necessary to sufficiently elevate the temperature in the heating chamber prior to putting food therein. That is, idle heating called pre-heating must be done. Neglectiny this would require a longer heating time or even cause a failure in cooking depending upon the kind of dish.
The other type is grill heating wherein food is baked by the radiant heat from the heat source. This type dose not require preheating since baking is carried out by the infrared radia-tion from the heat source. If preheating is performed by mistake, the interior of the heating chamber will reach a considerably high temperature in a short time , entailing danger. The user will be given a rough estimate of the required` heating time for grill heating under conditio~s not including unnecessary preheating;
thus, preheating would result ln a scorch.

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While the foregoing reEers to the difference based on the presence or absence of preheat:ing, there is another great difference in operation be-tween oven heating and grill heating. It lies in restart after the door is opened in the course of heating. Generally, -the heat source used for oven heating is a sheathed heater which emits less radiation, so that the heater itself takes some time in raising the temperature in the heating chamber. Thus, it is often so arranged that once heating is started, electric supply to the sheathed heater is continued even if the door is opened in between. Of course, temperature con-trol is performed. In shch case, therefore, oven heating is restarted simply by the user closing the door again.
On the other hand, used for the grill heating are a quartz tube heater and special sheathed heater which emit infrared radiation at high rates. These heaters exhibit a satisfactory rise in infrared radlation. There is no need to maintain the interior of the heating chamber at high temperature. Thus, if the door is opened during heating, electric supply to the heater will be cut off to protec-t the user against a burn. Thus, it is mos-tly so arranged that the start key myst be pressed again for restart.
Reference will now be given to such heating appliances as a microwave oven, equipped with a microwave generator, e.g., a nagne-tron. Microwave heating heats an object . ~

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~ 5 --internally and externally at the same time and needs no preheat:ing. If, therefore, preheating (i.e., idle heating) is efEected by mistake, though there is no danger of scorching as in grill heating this can be very dangerous since it results in an increased leakage of micrawaves from the main body and in overheating local portions of the heating chamber (where the standing waves are strong). Further, it damages the magnetron, shorten-ing its life. In other words, idle heating in the micro-wave oven is a strict prohibition.
For prevention of idle heating, the microwave oven must be so arranged that the s-tart key must be pressed before heating can be restarted, each time the door is closed.
As described above, the manner of operation widely differs according to differences in heat source and heating method. Moreover, composite heating appliances in which these oven, grill and microwave heating methods are integrated are coming to have a share of the greater part of the demand. Thus,the Nser should accurately remember and carry out the disparate operations for the respective heating methods. A mistake in these operations entails not only a failure in cooking but also possible dangers of hurting the person and even causing a fire.
Thus, prehea-ting has been a difficult thing particu-larly -to the cpmposite oven, as described above~ Moreover, preheating has the following problems left unsoLved.

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~2~ 7 How to carry out preheating -there are three methods, roughly clssified. ~ first method is to set a necessary preheating temperature and wait until heating -to this temperature. This is the intrinsic form of preheating, superior ln the functional aspect of elevati~g the tem-perature in the heating chamber to a predetermined value, and is capable of cpmpleting preheating in a shorter -time than any of the other methods which follow, though it dose not allow the user to leave the heating appliance since how long preheating will take is unknown.
A second method is to set a heating time alone and continue electric supply to the heater or the like serving as heating means until lapse of said time. The time at which preheating ends is obvious, so that this method is the most simple and convenient method for the user. However, since the preheating temperature is directly influenced by the heating chamber temperatue and the source voltage at the start of preheating, different preheating tem-peratures will result; thus, this method is inferior in functional aspect.
A third method, which is a combination of the preceding two methods, is to set both a preheating temperature and a preheating time. According to this method, after the preheating temperature is reached, temperature control is performed until lapse of the preset time; thus, this method is superior both in functional aspect ancl in operating aspect in that the preheating completion time is made known~

~L2;~37 As compared with the first method, however, it requres extra time and energy. The operating procedure is also increased, imposing an increased burden on the user.

DISCLOSURE OF THE INVENTION
With the above in mind, the present invention has for i-ts object the provision of a heating appliance which will never start heating until the user has set desired data on heating, will report to the user the acceptance of the effective heating data by the control system by using a synthsized voice or-other means to thereby make the operation readily understandable, and is capable of preventing the control system from running away even in the event of a failure.
Further, the invention realizes the provision of a heating appliance which notifies the user of the presence or absence of an object to be~heated and of the time for operating the start switch and which detects the open-ing and closing of the door to indirectly infer the pres-ence or absence of an object put therein so as to advance the heating sequence by one step, thus ensuring a safe operation.
The invention also provides a system adapted to complete heating with a minimum of time end energy involved and -to estimate and repor-t the preheating completion time.

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The above noted objects of the invention may be efected by providing: a hea~ing appliance comprising a heating chamber to receive an object to be heated therein, heating means connected to said heating charnber, a main control section for controlling electric supply to said heating means, a memory for storing data on heating, input means for inputtiny said data, timer means, and reporting means, the arrangement being such that when data on heating is inputted or corrected or corrected by said input means, said timer is started, and if there is no data inputted during the counting of a predetermined time, said main control section judges that the setting or correction of data on heating has been completed, and causes said report-ing means to make a report to the effect that it is possible to start heating.
The objects may be further ef~ected by providing:
a heating appliance comprising a heating chamber to receive an object to be heated therein, heating means connected to said heating means, a door installed on the opening in said heating chamber so that it can be opened and closed, means for detecting the opening and closing movement of said door, a main control section for controlling electric supply to said heating means, input means for inputting into registers data on heating temperature and heating time for a certaln ~7a-~w~g ~

heating operation or means for transferring these heating pattern data from a memory in which they are stored to predetermined registers, and reporting means for reporting the progress of heating, the arrangement being such that the main control section detects the opening and closing move-ment of said door by using said door opening and closing movement detecting means, controls the progress of the heating pattern set in said registers on th~Q basis of said detection, and causes said reporting means to report the essentials of operation necessary for the progress.
The above noted objects may be still furthQr effected by providing: a heating appliance comprising a heating chamber to receive an object to be heated therein, heating means connected to said heating chamber, sensor means capable of directly or indirectly detecting the temperature in the heating chamber, a main control sec~ion for controlling electric supply to said heating means on the basis of temperature information inputted by said sensor means, a memory having stored therein data on heating temperatures and heating times for performing certain heating operations, heating selection means for reading a heating pattern out of the memory and instructing the main control section to effect electric supply to the heating means in accordance with said heating pattern, and reporting means for reporting the progress of heatin~, the arrangement -7b-~z'2a~3~

being such that the main control section detects the temper-ature before or immediately after the start of heating by using said sensor, calculates or estimates on the basis of said detection an approximate time taken for the interior of the heating chamber to reach the predetermined temperature, and causes said reporting means to report said approximate time at least in two ways.

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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a prespective view of a main body, showing an emboidiment of the invention;
Fig. 2 is a detailed view of the principal por-tion of said main body;
Fig. 3 is a system block diagram of the same;
Fig. 4 is a circuit diagram, showing a concrete example of saidblock diagram;
Fig. 5 is a flowchart showing a program arrangement for detection of completion of setting;
Fig. 6 is a Elowchart showing a program arrangement for control of heating;
Fig. 7 shows a concrete e~ample of preheating con-trol; and Fig. 8 is a diagram showing temperature rise charac-teristics in a heating chamber.

BEST MODE OF CARRYING OUT THE INVENTION
Fig. 1 is a perspective view of the main body of a heating appliance, showing an embodiment of the invention.
The main body 1 has a door 2 pivotally mounted on the front surface thereof, said body being provided with an operating panel 3. Arranged on the operating panel 3 are a keyboard 4 and numerical-value setting knobs 5 serving ~25 as input means enabling the user to give various instruc-tions to the control system. The numeral 6 denotes an indicator window Eor indicating heating data which is se-t ~... ~ . . ` .
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^ _ 9 _ through said input means, and 7 deno-tes a vocal port for delivering synthsized voices.
Fig. 2 is a detailed view of the principal portion.
Arranged on the keyboard 4 are various function keys 'i or giving instructions on heating modes to the control sys-tem. The numerical-value setting knobs comprise a ~lme knob 5a for inputting "time/weight" and ~ temperature knob 5b for inputting "temperature". The time knob 5a is capable of inputting a heating time for each mode and the ]0 weight of an object to be heated for a "weight thawing"
mode, while the temperature knob 5b is capable of inputting chamber temperatures for grill and oven modes.
Arranged in the indicator window 6 are a numeral indicating section 6a for indicating a heating time or weight, temperature bars 6b for indicating temperatures, and a mode status 6c for indicating heating modes.
A weight thawing key ~ is used to cause the control system to calculate the heating time by inputting the weight o~ an object to be heated; thus, it clears the user of the burden of conversion to the heating time.
At this time, in the indicator window 6 a "g" status 6b is lighted to indicate the inputted weight.
A start key 9 is used to give an instruction to star-t heating and a clear key 10 is used to stop heating or cancel a program.
Fig. 3 is a block diagram showing the system arrange ment of the heating appliance. In~talled in a heating ~: ... . . . ...... ., . ., ~_, , ..

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chamber 11 are a magnetron 12 and heaters 13 and 14, which are heating means, -to supply -thermal energy to an object to be heated 15. Electric supp:Ly to these heating means is controlled by a main control section 16. The S numeral 17 denotes an electric supply control section including switching means, such as a relay, and a driver for dri~ing it.
Data on heating is inputted into the main control sec-tion 16 from the keyboard 4 and also from volumes 18a, 18b connected to the knobs Sa, 5b. The numeral 19 denotes an A/D converter for reading in the resistance values of the volumes. Suçh volumes may be constructed of a rotary encoder. The data on heating inpu-tted by such input means is stored in a RAM in the main control section ]5 16. Heating is controlled on the basis of da-ta on heating.
Further, such da-ta on heating is displayed by display means 20.
The openingandclosingmovement of the door 2 is detected by a door switch 21 serving as door opening and closing detecting means and is inputted into -the main control section 16.
The numeral 22 denotes a thermistor serving as sensor means for detecting the temperature in the heating chamber 11. The numeral 23 denotes a detection circuit B for reading variations in the resistance value of the thermistor and inputting them into -the microcomputer, said detection circuit being construc-ted, e.g., of an A/D

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converter.
The numeral 24 denotes a detection circui-t C for monitoring -the source voltage. It may be constructed, e.g., of an A/D converter or it may be a comparison circuit for comparison with a reference voltage, formed of a simpler device, e.g., a zener diode.
VoLce synthesizing means comprises a synthesizer 25, a voice memory 26, and a speaker 27.
The voice memory 26 has voice data stored therein to allow the synthesizer 25 to read out said voice data so as to synthesize voice signals. These voice signals are transferred to the speaker 27 and converted into voices.
The numeral 28 denotes a sensor for detecting the progress of heatingl and 29 denotes a detection circuit therefor. The sensor 28 may be in the form of a ther-mistor for detecting the temperature in the hea-ting chamber 11, a humidity sensor for detecting vapor being evolved from -the object 15, or an infrared sensor for detecting infrared rays being emitted from the object 15.
Fig. 4 is a circuit diagram showing an embodiment of said system. The main control section 16 is constituted of a controller of the stored program type, e.g., a one-chip microcomputer. Such microcomputer 16 controls electric supply to the magnetron 12 or to the heaters 13, 14, through a relay driver representing the electric supply control section 17. A time relay 30 is a relay .. . .
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adapted to be continuously closed during this electric supply. A power relay 31 is a relay adapted to be intermittently closed during this electric supply and a~t to change the average output from the magnetron 12 or heaters 13, 14. The numeral 32 denotes a switchlng relay for controlling switching between the magnetron 12 and the heaters 13, 14.
In addition, 33 denotes a main circuit door sw:itch for breaking and making the main circuit in response to the opening and closing of the door; 34 denotes an interior ]amp; and 35 deno-tes a motor for a cooling- fan or the like.
Data on heating are inputted into the miCrQcomputer 16 from the keyboard 4 and from the volumes l~a, 18b.
A/Dl and A/D2 denote A/D input terminalsl containing A/D
converters. The keyboard 4 has a key matrix built thereon, swept by outputs Ro~R3 and connected to input terminals I -I .
The do~r switch 21 is swept by an output R4 znd connected to the input terminal I3.
The sweep outpu-ts from the key matrix also serve as grid control signals for the fluorescen-t display tube 20 capable of dynamic lighting. The display -tube 20 comprises 6 grids and obtains display data from outputs O0-O7.
The arrangement of various sensor means will now be described. The numeral 22 denotes a thermistor or detecting the -temperature in the heating chamber. It l~

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is connected to the A/D input terminal A/D3. The numeral 28 denotes a humidity sensor which detects the progress of heating. It is connected to A/D4. The numeral 24 ~ denotes a source voltage monitor which detects the voltage S in -the main circuit. It is connected to A/D5.
Also inputted into the microcomputer 16 is a clock slgnal which forms a basis for timer counting. The numeral 36 denotes a clock circuit therefor.
The voice synthesizing means comprises the voice syntheslzer 25, voice memory 26, and speaker 27. For this synl:hesizer, for example, LSI based on PARCOR synthesizing method is employed. The numeral 37 denotes an audio amplifier which drives the speaker 27. The readout address is outputted from the microcomp~ter 16 through Do-D3.
The microcomputer 16 controls the synthesizer by means of Rg signal and I4 input.
In such arrangement, the procedure for inputting data on heating and the method of control associaLed therewith will now be described.
Fig. 5 is.a flowchart illustrating such procedure and control. First, the microcomputer 16 waits for a key 4 to be pressed, while displaying "O", (a).
When a key 4 is pressed, the mlcrocomputer decodes it (b), and sets the corresponding heatlng mode (c).
Thus, the set heating mode is displayed on the display tube 20, with "O" disappearing and with -the digit places bei.ng all blank.

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. _ 3?7 In this condltion, the microcomputer 16 waits for the volume 18 (18a, 18b) to be turned (d). As soon as the volume 18 is turned, the microcomputer resets the interior timer (e) and starts counting up (f). At this time, a heating time which has been set appears in the display tube 20.
~hen the interior timer counts a predetermined time (2 seconds, in this example), -this results in time-up (g). If the volume is turned again during this time (h), the microcomputer judges that the setting of heating ti.lne has not been completed, and it resets the timer again and counts 2 seconds afresh. That is the sequence will not proceed until the end of fine adjustmènt of heating time made by the volume 18, followed by lapse of 2 seconds.
: Upon lapse of 2 seconds, the microcomputer 16 outputs a predetermined voice selection signal to the synthesizer 25 and reports the completion of setting through the speaker 27 (i). For example, in the case of grill heating and microwave heating, it reports in synthesized voice, "Put in your food and then press the cooking start key."
In the case of oven heating, it voices a warning. "Pre-heating takes place first. With nothing pu-t in, press the start key." Thereafter, the microcomputer 16 waits fox the start key to be pressed.
The provision of such sequence ensures that operation wi:ll not be started by mistake even iE -the star-t key is . , ,. ... , . ., .,~ ,,~ .

pressed when a heating time and temperature are not set or are being set or even if noise causes misunderstanding.
Further, even if the start key is dameged and remains ON
or even if the volume brush and resistance pa-ttern get out of order, the normal sequence is protected from being executed, thus preventing start of heating. The former results in the on-state of the start key being detected before the volume is turned, so that such is neglected.
The latter results in the volume value fluctuating rather than stabilized, so that the timer cannot count 2 seconds.
~rhus, the invention is not seriously influenced by actual parts failures.
In addition, the setting completion report may be made by a display tube, still providing the same effect.
However, the synthesized voice provides a higher warning effect and is more concre-te.
Further, it is also possible to make a report con-cerning the sensor 28 by using the voice synthesizing section. For example, in the case of such a humidity sensor as ~umiceram, as the temperature in the heating chamber 11 rises, the humidity sensor exhibits thermistor characteristics, failing to detect humidity changes.
Thus, a thermistor and a humidity sensor may be provided as the sensor means and a program may be so prepared that if the temperature in the heating chamber rises above a certain level, a report is made to -the effect that automatic cooking is impossible.

~2~3~7 An arrangement for advancing the heating sequence depending upon the opening and closing movement of the door will not be described with refexence -to Fig. 6.
After setting data on heating, the user opens the door, puts an object ta be heated in the heating chamber, and closes the door again. Thus, the micro-computer can indirectly detect the placement of an object in the heating chamber, from the opening and closing movement of the door (j). Then, it advances the heating sequence by one step, and waits for the start key to be pressed. At the same t-ime, it makes a report urging the user to do that, ("Press the s-tart key.") In the case of oven heating, such operation on the door is normally not performed, but if it is performed, there isa possibility-that an object to be heated has been placed by mistake, Thus, the microcomputer urges the user to do the idle heating again, ("With nothing put in,-press the start key.") With an object to be heated placed or removed, as requested, the-start key is then pressed (k). Thereupon, the microcomputer starts electric supply to the indivi-dual heating means and reports that heating is going to be started, ~"Cooking begins.") In the case of oven heating, an estimated preheating time report Z is made, ("Preheating will be over in about X minutes.") (This will be later described in more detail.) In addition, if the start key is pressed wi.-thout ~22~f~37 passing through the state j, i.e., without the opening and closing of the door, -the microcompu-ter judges that idle heating has been performed, and it will not start electric supply to the heating means except for oven heating. Thus, the danger of performing idle heating is eliminated. In addition, the order of performing key operation and object placement may be reversed.
In this case, nothing will be reported since preparation for preheating is not completed at the time of placement.
Suppose that the door is opened during heating (1).
Thell, in the case of grill heating and oven heating, the step j is followed, ("Press the start key."); in the case of oven heating, the user i~s requested to continue idle heating, ("Don't put in food until com-pletion of preheating.") In this case, since it is undesirable to lower the heater temperature, electric supply to the heater is not stopped. Therefore, once the door is closed, preheating is continued, so that operation on the start key is not required nor is a report made urging the user to do that.
After restart, time-up or the heating temperature is reached (m), whereupon a report of the completion of heating is made, ("It's finished.") In the case o oven heating, the completion of preheating and a request for placement of an object are announced, ("Preheating is ovex. Put in your food and then press the star-t key. Il) Subsequent placement of an object to be heated (n), ~22~3';7 operation on the start key, and report oE time-up or of attainment of heating temperatu e (o) are the same as in grill and microwave hea-ting.
While synthesized voices have been used as report~
ing means in this embodimen-t, other reporting means, such as display tubes and LEDs are applicable, of course.
In Fig. 6~ it will be recalled that an estimated preheating time report Z was executed; that is, it was a report saying, "Preheating will be over in about X
minutes." This is per~ormed by the thermistor 22 detecting the temperature in'the heating chamber before or immediately after the start key is pressed and by the monitor 25 measuring the source voltaye.
On the basis of such measurements, the micro-computer 1~ outputs the temperature of preheating to be e~fected first i'nto the display section or the fluore-scent display tube 20, estima-tes the time required for the preheating, and reports said time in synthesized voice through the voice synthesizing section comprising the synthesizer 25, voice memory 26 and speaker 27.
While monitoring the source voltage is indispens-able for strict estimation of preheating time, the ~ollowing expedient may be contemplated. Fig. 7 shows a concrete embodiment oriented to automatic oven heatingO
Suppose that a key for automatic cooking 3 is pressed.
Then, the microcomputer produces a buzzer sound (pi) and then reports the name of the menu corresponding -to ~ r ~ ~' ' 33~
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the heating pattern, ("It's a butter roll.") Further, - the display tube 20 outputs display data "~3" to indicate that automatic cooking 3 has been effectively accepted.
The syntheslzer 25 subsequently reports that the pre-heating sequence has been preset, ("Preheating takes place first.") When the start key is pressed, the microcomputer 16, as already described, calculates or estimates the time taken to reach the preheating temperature, from the tem-perature in the heating chamber, and reports it in synthesized voice, ("Preheating will be over in about 8 minutes.") The estinlated time is also displayed by the numeral display section 6a. In the e~ample shown in Fig. 7, whether the temperature in the heating chamber is above 100C or not is taken into account in connection with processing, the former case being referred to as hot start and the la-tter as cold start. In the case of hot start, a standard period of time (8 minutes) taken to reach the preheating temperature (180C) for butter rollsis reported, while with cold start a shorter period of time is reported,("in a few minutes" or "in 2 -to 3 minutes"). As for temperature indication, the preheating completion temperature is indicated by lighting and the present time by blinking.
Upon completion of preheating, several times of buzzing is followed by a report of the completion oE
pxeheating. ("Preheating is over.") Continuing temperature .

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eontrol, the microcompllter waits for -the user to come (wait cycle). Knowing an approximate -time of preheating completion, the user will come back to the heating appliance before that time. That is, without requiring S constant attendance on the part of the user, such wait time can be made very short~ Thus, the merit of the first conventional method (a minimum of preheating time and energy) and the merit of the second (knowable pre-heating completion time) can be combined, and the wasteful wait time and troublesome operation involved in the third method are no longer required.
After wait cycle, when the user opens the door, the microcomputer 16 makes a report about the cooking proce-dure for main heating and about the attachments which must be (or can be) used, ("Baking is by two-stage cooking.
Put your food in the footed plate.") Whereas in a heating appliance ofthe microwave and hot oven combination type the differential use ofvarious at-tachments has been inevitable (e.g., metal plates for hot oven and glass plates for microwave oven), the invention enables these plates to be readily used each in its proper way.
Thus, the combined use of synthesized voices and temperature sensors in the manner described above has made it possible to e~ecute -the heretofore troublesome preheating sequence in a simple operation ~ree from errors.
A method of more strictly estimating preheating time by using the source voltage monitor 24 will ~ow be . . . ,. ~ ~ . . - ;, ~L2~3~

described. Fig. 8 is a graph showing heating chamber temperature rise characteristics. Curve A represents a standard pa-ttern starting at room -temperature, showing that it takes 8 minutes for the temperature to reach 210C. If the source voltage changes, the temp~rature gradient also changes. Curves B and C represent character-is-tics at 110% voltage and 90~ voltage, respectively.
In the case of cur~es B and C, the standard time TS must be corrected by an amount of QTl (1 minute) and ~T2 (1-2 minutes), respectively, and the corrected times will be reported.
A manner of starting with the heating chamber already heated to a certain extent will now be described. Curves D and E predominate in thls case. Curve D represents a situation where the heating chamber has considerably cooled, i.e., some amount of time has passed since the last hea-ting.
The temperature in the region around the sensor is still high, so that when stirring begins, the temperature in the heating chamber becomes uniform, causing the temperature around the sensor to drop temporarily. In such case, therefore, though the sensor has already reached 100C
it does not follow that it is correct to sub-tract ~ minutes from the standard pattern A. Actually, it takes 5 minutes.
The other curve E is found in a situation where heating is interrupted on the way. That is, while the heater chàmber is su~iciently high in temperature, the temperature in the region around the sensor has not risen.

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An example of this case i5 where the doox is opened during preheating and preheating is restarted. In this case, the preheating completion time is shorter than 4 minutes, being reduced to about 3 minutes.
Thus r ifthe temperature in the heating chamber and the source voltage at the start of heating can be rneasured and if the tendency of temperature rise immediately after the start of heating can be detected, the preheating time can be estimated with substantial accuracy. Accordingly, temperature display can be provided by the display section and a rough estimate oE the preheating time can be provided by the voice synthesizer and display tube. While synthe-sized voices have been used as reporting means in the present embodiment, other reporting means such as display tubes and LEDs may be used in place of synthesized voices~
It is a matter of course that the voltage to be measured in the source voltage monitor 24 can be used as DC power source for the control system. Since any trouble such as momentary power failure can be detected as soon it occurs by virtue of said measurement, the microcomputer 16 can be forced to reset itself when it is in normal operation, to thereby prevent the microcomputer from running away.

INDUSTRIAL APPLICABILITY
As has been described so far, according to the present invention, in a hea-ting appliance having a digital con-trol ... ..

~2~37 section, there is no possibility of heating being started by mistake before data on heat-ing is set. Effective heating data is accepted and the next operation is reported in synthesized voice, etc., lhe operation is easy to understand. In the event of a failure, the normal sequence is prevented from proceeding, so that there is no possibility of heating being started.
By detecting the opening and closing movement of ~ the door, placement of an object to be heated in the heating chamber is indirectly ascertained, the time for such placement being reported to make it sure. On the basis of these features, safety means can be realized.
Additionally, in a heating appliance which requires preheating, the procedure for preheating, including estimation of the time of completion of preheating, is simple and easy and can be efficienty carried out.

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Claims (14)

CLAIMS:

1. A heating appliance comprising a heating chamber to receive an object to be heated therein, heating means connected to said heating chamber, a main con-trol section for controlling electric supply to said heating means, a memory for storing data on heating, input means for inputting said data, timer means, and reporting means, the arrangement being such that when data on heating is inputted or corrected by said input means, said timer is started, and if there is no data inputted during the counting of a predetermined time, said main control section judges that the setting or correction of data on heating has been completed, and causes said reporting means to make a report to the effect that it is possible to start heating.

2. A heating appliance as set forth in Claim 1, including voice synthesizing means as said reporting means.

3. A heating appliance as set forth in Claim 2, wherein when said main control section judges that the setting of data on heating has been completed, said voice synthesizing means makes a report to the effect that operation on heating start instruction means is requested.

4. A heating appliance as set forth in Claim 1, wherein said input means is in the form of a volume having a rotatable knob, or of a rotary encoder or the like.

5. A heating appliance as set forth in Claim 1, wherein data on the weight of an object to be heated can be inputted by said input means, and the main con-trol section calculates the heating time from said data.

6. A heating appliance as set forth in Claim 5, including display means whereby the weight is displayed when data on heating is set, and the heating time calculated by the main control section is displayed when it is judged that the setting has been completed or when heating is started.

7. A heating appliance arranged so that a main control section will not start electric supply to heating means until it is judged that the setting of data on heating has been completed, even if heating start instruc-tion means is operated.

8. A heating appliance comprising a heating chamber to receive an object to be heated therein, heating means connected to said heating means, a door installed on the opening in said heating chamber so that it can be opened and closed, means for detecting the opening and closing movement of said door, a main control sec-tion for controlling electric supply to said heating means, input means for inputting into registers data on heating temperature and heating time for a certain heating operation or means for transferring these heating pattern data from a memory in which they are stored to predetermined registers, and reporting means for reporting the progress of heating, the arrangement being such that the main control section detects the opening and closing movement of said door by using said door opening and closing movement detecting means, controls the progress of the heating pattern set in said registers on the basis of said detection, and causes said reporting means to report the essentials of operation necessary for the progress.

9. A heating appliance as set forth in Claim 8, including a voice synthesizing section as said report-ing means, whereby the essentials of operation necessary for execution of the heating pattern are reported in synthesized voice.

10. A heating appliance as set forth in Claim 9, wherein said essentials of operation necessary for execu-tion of the heating pattern include information on whether or not it is time for an object of heating to be placed in the heating chamber, and such informa-tion is reported by said reporting means in accordance with individual heating patterns.

11. A heating appliance as set forth in Claim 8, wherein said control section includes heating start instruction means, and upon completion of the inputting of heating pattern data into said registers or upon detection of the closing movement of the door by said door opening and closing movement detecting means, said reporting means makes a report urging the operation of said door opening and closing movement detecting means.

12. A heating appliance comprising a heating chamber to receive an object to be heated therein, heating means connected to said heating chamber, sensor means capable of directly or indirectly detecting the temperature in the heating chamber, a main control section for control-ling electric supply to said heating means on the basis of temperature information inputted by said sensor means, a memory having stored therein data on heating tempera-tures and heating times for performing certain heating operations, heating selection means for reading a heat-ing pattern out of the memory and instructing the main control section to effect electric supply to the heat-ing means in accordance with said heating pattern, and reporting means for reporting the progress of heating, the arrangement being such that the main control sec-tion detects the temperature before or immediately after the start of heating by using said sensor, cal-culates or estimates on the basis of said detection an approximate time taken for the interior of the heat-ing chamber to reach the predetermined temperature, and causes said reporting means to report said approximate time at least in two ways.

13. A heating appliance as set forth in Claim 12, including a display section and a voice synthesizing section as said reporting means, wherein said display section displays the heating temperature or the present temperature in the heating chamber, while the voice synthesizing section reports an estimated time required to reach the predetermined temperature by using a syn-thesized voice.

14. A heating appliance as set forth in Claim 12, including means for detecting source voltage, and where in said means is used to measure the source voltage before or immediately after the start of heating, an approximate time required for the interior of the heat-ing chamber to reach the predetermined temperature is calculated or estimated from the measured value of said source voltage, and said approximate time is reported by said reporting means.