`Tuckeret al.
`
`119)
`
`fy]
`[45]
`
`4,308,443
`Dec. 29, 1981
`
`INDUCTION COOK-TOP WITH IMPROVED
`TOUCH CONTROL
`
`Inventors: Raymond M.Tucker; Ciarence L.
`Dyer; Gregory P. Maman,all of
`Cleburne, Tex.
`
`
`
`[54]
`
`[75]
`
`[56]
`
`3,775,577 11/1973 Peters, Jr. cecescssseseese 219/10.49 R
`
`3,777,094 12/1973 Peters, Jt. cue. 219/10.49 R
`3,781,503 12/1973 Harnden, Jr. etal.
`...... 219/10.49 R
`3,781,504 12/1973 Harnden, Jr. «0... 219/10.49 R
`
`3,781,506 12/1973 Ketchum............cc0 219/10.49 R
`
`
`3,781,508 12/1973 Steigerwald................ 219/10.49 R
`.
`1/1974 Kornrumpfetal.
`........ 219/10.49 R
`3,786,219
`[73] Assignee: Rangaire Corporation, Cleburne,
`3,786,220
`1/1974 Harnden, Jr. ssc 219/10.49 R
`Tex.
`3,786,222
`1/1974 Harnden, Jr.et al.
`...... 219/10.49 R
`3,796,850
`3/1974 Morelandetal............ 219/10.49 R
`[21] Appl. No.: 35,083
`3,806,688 4/1974 Mackenzieetal........... 219/10.49 R
`
`‘ed:
`6/1974 Bowersetal. .............. 219/10.49 R
`3,814,888
`
`
`
`[22]|Filed: May1, 1979 3,820,005 6/1974 Steigerwald..... . 219/10.77 X
`
`
`
`7/1974 Cunningham ........... 219/10.77
`[S21] Ent. CRS ce eeesetees HOSB 6/06; HOSB 6/12;
`3,823,297
`
`. 219/10.49 R
`GO08C 9/02
`3,843,857 10/1974 Cunningham ....
`
`
`ae yove MoCleerey et ab. ... 219/iota R
`[52] US. Ch. cneeecceeeeecsseteceneee 219/10.49 R; 219/10.77;
`Ir. ce ecesecreeee 219/10.49 R
`.
`.
`.
`:
`886,
`eters,
`......seceseseres 219/10.49 R
`219/506; 307/116; eyOODIGE
`3,887,781
`6/1975 Peters, Jr.
`
`
`.............00 200/DIG.1
`.
`;
`,
`3,887,848
`6/1975 Larson etal.
`6/1975 Makenzie ................. 219/10.49 R
`[58] Field of Search.................... 219/10.77, 10.49 R,
`3,889,090
`
`8/1975 Peters, Ir. cescssessssessn 219/10.49 R
`219/10.55 B, 445, 453, 459, 492-494, 490, 497,
`3,898,410
`
`9/1975 Hibinoetal. ecco 219/10.49 R
`499, 501, 506; 200/DIG.1; 307/116, 126, 96,
`3,906,181
`. 219/10.49 R
`97, 308, 252 K, 252 M,238, 239, 296; 363/57,
`3,925,633 12/1975 Partridge.........
`
`we. 307/116 X
`..
`135, 95, 96; 361/94, 97; 328/48, 71, 5; 340/365
`3,927,336 12/1975 Carlson et al.
`
`3,928,744 12/1975 Hibinoetal. ................ 219/10.49 R
`S, 365 C, 365 E, 366 R, 382, 716; 235/92 CT,
`
`1/1976 Peters, Jr.....
`219/10.49 RX
`92 EV, 92 PE; 323/101
`3,932,801
`3/1976 Cobb... esssscesesesserseeres 219/10.79
`3,947,652
`...scsesessseeee 219/10.49
`3,949,183 4/1976 Usami et al.
`References Cited
`
`3,953,783 4/1976 Peters, Jr.....
`219/10.49 R X
`
`6/1976 McCoyetal.
`. 219/10.49 R X
`3,966,426
`U.S. PATENT DOCUMENTS
`8/1976 Gould, Jr. 00...
`eee 219/506 X
`3,974,472
`3,530,310 9/1970 Adelsonetal. ............008 340/365 C
`
`. 219/10.49 R
`4,010,342
`3/1977 Austin .......
`we 219/10.49 R
`3,530,499 9/1970 Schroeder.....
`
`
`3/1977 Fosnoughetal.
`. 219/10.55 B
`4,011,428
`1/1972 Cunningham ...........c0 219/10.75
`3,637,970
`
`
`9/1977 Sefton et ab. oo...
`ceceseees 219/497
`4,046,991
`3,697,716 10/1972 Kornrumpf...
`219/10.49 R
`
`. 219/10.49 R
`4,074,101
`2/1978 Kiuchiet al.
`a 219/10.49 R
`3,697,717 10/1972 Kornrumpf...
`
`
`
`3/1978 Hamilton ........cccseeeceees 328/5 X
`4,081,700
`eee 200/167 R
`3,701,869 10/1972 Jacob et al.
`340/365 E X
`8/1978 Iwai etal. .
`4,105,902
`ve 219/10.49 R
`3,710,062
`1/1973 Peters, Jr.
`.
`
`
`4,149,217 4/1979 Tucker .0.......cececsstceeeneeees 219/10.77
`a 219/10.49 R
`3,711,672
`1/1973 Moreland......
`6/1979 Mason ...esscesssssssssssssesseeee 219/506 X
`4,158,759
`.. 219/10.49 R
`3,715,550 2/1973 Harnden,Jr. .
`
`3/1973 Harnden,Jr......
`w 219/10.49 R
`3,719,789
`OTHER PUBLICATIONS
`6/1973 Kornrumpfetal. ws. 219/10.41
`3,742,173
`3,742,174 6/1973 Harnden,Jr. .
`“Power on Reset For Machine Circuits”, IBM Techni-
`» 219/10.49 R
`3,742,175
`6/1973 Harnden,Jr. .
`cal Disclosure Bulletin, vol. 9, No. 6, Nov. 1966.
`- a149 k
`.
`3,742,178
`6/1973 Harnden,Jr. .
`.
`G.E. Semiconductor Products Department, “A Low
`3,742,179
`6/1973 Harnden,Jr. .
`we 219/10.49 R
`
`Cost, Ultrasonic Frequency Inverter using a Single
`3,742,337
`6/1973 Digneffe 0.0... cssseeseerees 307/252 B
`SCR,” Note 200.49, Neville Mapham, Feb., 1967.
`...... 219/10.49 R
`3,745,290 7/1973 Harnden,Jr.et al.
`:
`“
`;
`:
`7/1973 Wilt oo...csecsssenesscnstaseesseeses 340/382
`3,745,450
`:
`
`
`3,761,667|9/1973 Walden ecsssssessnencen 219/10.49 R _Environmental/one, “Annual Report, Licensing Busi-
`
`
`
`...... 219/10.49 R
`3,761,668. 9/1973 Harnden,Jr. et al.
`ness .
`3,770,928 11/1973 Kornrumpfetal. ........ 219/10.49 R
`IEEE Transactions on Industry Applications, “The
`
`1
`
`_ APPLE 1019
`
`1
`
`APPLE 1019
`
`
`
`4,308,443
`
`Page 2
`
`Induction Range: Its Performanceand Its Development
`Problems”, W. C. Moreland II, Jan./Feb., 1973, vol.
`1A-9, No.1.
`IEEE Transactions on Industry Applications, “A Por-
`table Cool-Surface Induction Cooking Appliances”,
`Philiph, Peters, Nov./Dec. 1974, vol. 1A-10, No. 6.
`“Induction Range Circuits—Past, Present, Future”, Jul.
`30, 1973.
`“Non-Heating Range Using Induction Method”, Mit-
`subishi Electric Corp.
`RCA,Solid State Division, Thyristors and Rectifiers
`“Characteristics and Applications of RCA Fast-S-
`witching ASCR’s”, Application note AN6456, Henri
`Digneffe, Jan. 1976.
`“Solid State Power Control Program”, Dr. Richard G.
`Hoft, Aug. 21, 1973.
`Primary Examiner—Gene Z. Rubinson
`Assistant Examiner—Philip H. Leung
`Attorney, Agent, or Firm—Richards, Harris & Medlock
`
`ABSTRACT
`[57]
`An induction heating system (40) is provided and in-
`cludes a plurality of induction heating coils (118).
`Touch control pads (50, 52, 70, and 72) are provided
`together with circuitry (80) for generating energization
`- control signals. Circuitry (112 and 116) is provided for
`electrically energizing the induction heating coils (118).
`Anelectronic digital processor(82) is responsive to the
`energization control signals for generating energization
`signals for actuating and controlling the energization
`circuitry (112 and 116) to thereby vary the energization
`of the plurality of induction heating coils (118). Cir-
`cuitry (150 and 152) is provided for maintaining touch
`control pads (50, 52, 70 and 72) operable when an opera-
`tor is in contact with a pan disposed adjacenttheplural-
`ity of induction heating coils (118).
`
`13 Claims, 24 Drawing Figures
`
`2
`
`
`
`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet 1 of 22
`
`4,308,443
`
`
`
`
`
`
`
`
`
`
`3
`
`
`
`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet:2 of 22
`
`4,308,443
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`Dec. 29, 1981
`
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`
`4,308,443
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`U.S. Patent
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`Dec. 29, 1981
`
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`4,308,443
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`Dec. 29, 1981
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`Dec. 29, 1981
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`4,308,443
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`
`Dec. 29, 1981
`
`Sheet 8 of 22
`
`4,308,443
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`U.S. Patent
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`Dec. 29, 1981
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`Sheet 9 of 22
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`4,308,443
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`Sheet 10 of 22
`
`4,308,443
`
`Dec. 29, 1981
`
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`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet 11 of 22
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`4,308,443
`
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`13
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`
`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet 12 of 22
`
`4,308,443
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`Dec. 29, 1981
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`4,308,443
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`Dec. 29, 1981
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`PROCESSING
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`672
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`Sheet 15 of 22
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`4,308,443
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`
`
`
`
`956
`
`972
`
`980
`
`R41
`
`964
`
`988
`
`
`996
`
`My]
`
`SET
`R41=0
`SET
`B COUNT=9
`
`958
`:
`
`974
`
`:
`
`982
`
`R42
`
`998
`
`
`
`990
`Y
`
`SET _
`
`aneC_COUNT=O_
`
`;
`
`|
`
`4
`
`98
`
`992
`y
`
`1000
`
`[Set 0
`sex
`id COUNT=0
`
`976
`
`960
`:
`
`976
`
`“
`
`968
`
`
`
`
`,
`SCAN LOCK &
`SET R43-0
`UNLOCK PADS
`
`ROUTINE
`
`
`
`
`SET R8=0
`
`370
`
`FIG. 16
`
`17
`
`17
`
`
`
`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet 16 of 22
`
`4,308,443
`
`40SEC TURN OFF J
`ROUTINE
`
`674
`
`CLEAR BITS 4 &5
`OF I/O PORT 4 BY
`
`WRITING A O SET UPPER 5 BITS
`
`“OR' WITH
`FAN BIT
`
`SET BIT 6 OF
`PORT 4 =RESULT
`
`OF R11=00101
`
`1034
`
`SET LKCT-100
`
`N
`
`DISABLE UP CMDS
`BY SETTING BIT 1
`OF R30 TO 1
`
`R30 EO ? oF
`
`FIG. 17
`
`18
`
`18
`
`
`
`Sheet 17 of 22
`
`4,308,443
`
`Y
`
`1050
`
`N
`CLEAR PORT O
`
`READ PORT O
`
`1052
`
`1054
`
`N
`
`7058
`
`1066
`
`1074
`
`/oe
`
`
`
`
`
`SET MUX
`
`1068
`
`1076
`
`1084
`
`4
`j
`
`_|
`
`U.S. Patent
`Dec. 29, 1981
`oun 682
`ae
`
`
`
`SEa A COUNT
`SETMUX
`Oo 20
`BCOUNT
`SET MUX
`Cee CCOUNT
`N|DECREMENTPEHe
`
`B
`N.{DECREMENT
`COUNT
`
`
`
`
`1070
`1078
`
`1060
`
`Y
`
`062
`
`Y
`
`1064
`
`Y
`
`N
`
`[DECREMENT
`
`
`
`
`1072
`1080
`
`1086
`
`1088
`
`;
`PAD'
`BSOHWE 0S|s688
`
`19
`
`
`
`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet 18 of 22
`
`4,308,443
`
`SCAN DOWN
`PADS ROUTINE
`
`§ 686
`
`“Tt
`
`
`
`N00
`
`694
`
`N
`
`|
`~
`FLASH ACTIVE
`ELEMENTS ROUTINE H
`
`oO
`
`Ky
`
`Bir
`
`s
`
`ELEMENT ROUTINE
`
`N|A COUNT N_ JA COUNT = }
`
`pd
`ry
`1108
`
`1110
`
`112
`
`18
`
`1114
`
`i116
`
`N
`
`B COUNT
`
`y
`
`N_]|B COUNT =.
`
`SET
`
`
`
`[READRTO] sp
`
`I
`008
`1110
`1118
`1116
`
`7? 30
`<u> couri0|
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`
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`[RenoPorro1106acoun 100
`
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`N_[c¢ COUNT
`N_[C COUNT =
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`ne ee
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`a
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`:
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`_{D COUNT
`
`i
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`1118
`[DB COUNT=
`
`N
`
`1NN6
`
`Had
`
`D COUNT =100 |
`
`1114
`
`FIG. 19
`
`AN FOR TURN OFF §
`COMMANDS ROUTINE 4
`
`692
`
`20
`
`20
`
`
`
`U.S. Patent
`Dec.29, 1981
`ROUTINE
`
`SCAN UP PADS
`
`Sheet 19 of 22
`
`4,308,443
`
`
`
`690
`
`VERIFY SELECTED
`ELEMENT SETTING
`ROUTINE
`
`
`
`688
`
`SCAN UP PADS
`ROUTINE
`
`
`
`21
`
`21
`
`
`
`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet 20 of 22
`
`4,308,443
`
`ee
`ROUTINE
`
`692
`
`682
`
`
`
`
`¥
`;
`L
`IT
`U
`
`SET CLOCK
`ACTIVE =}
`
`
`1182
`
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`
`1192
`
` ELBEASWire
`
`Y
`INCREMENT
`MINUTES UNITS
`
`
`i
`
`|
`
`
`1194 Ges>
`
`1196
`
`SET HOURS=1
`
`;
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`
`MINUTES
`=0
`ET
`
`UNITS =O
`
`1198~ TNCREMENT
`MINUTES TENS
`
`|
`
`1202
`
`1200 MS
`
`
`
`f
`SET MINUTES
`TENS =0
`
`22
`
`22
`
`
`
`CLOCK SETTING
`ROUTINE
`
`SCAN UP PADS
`ROUTINE
`
`4,308,443
`
`688
`
`U.S. Patent
`Dec. 29, 1981
`Sheet 21 of 22
`684
`
`
`
`
`1236
`
`SET R20
`
`1232
`
`,
`
`B COUNT
`
`1232
`1234
`SET R2O
`N
`Y
`SET R20
`BIT 2 =]
`BIT 2=0
`
`
`
`
`1236
`
`1234
`
`1232
`
`1236
`
`BIT3=0
`
`BIT 3 =]
`
`SET FLASH R20
`
`1240
`
`1242
`
`1244
`
`1246
`
`N
`
`STORE
`
`IN
`
`1248
`
`1250
`
`N<>
`
`1252
`
`658
`
`DISABLE
`INTERRUPTS
`
`4
`|
`
`FIG. 23
`
`23
`
`
`
`U.S. Patent
`
`Dec. 29, 1981
`
`Sheet 22 of 22
`
`4,308,443
`
`STACK
`
`r 1260
`
`MAINTANENCE
`
`FETCH MUX
`
`1278
`
`1280
`[coupcewentJ
`
`AND WITH
`PORT 4
`
`z
`OUTPUT TO
`PORT 4
`
`1282
`
`1284
`
`
` 1286
`AND PORT_4
`
`
`LOWER BITS
`WITH PORT 5
`
`
`LOWER BITS
`
`
`FIG. 24
`
`24
`
`
`
`COMPLEMENT
`RESULT
`
`EXCLUSIVE OR
`WITH INTERRUPT
`SOURCES
`
`
`
`SET PORT 4
`BIT 7=0
`
`WAIT 3OMSEC
`
`SET PORT 4
`BIT 7 =1
`
`STACK
`MAINTANENCE
`
`PREVIOUS
`ROUTINE POSITION
`
`1310
`
`1312
`
`, 1314
`
`1316
`
`24
`
`
`
`INDUCTION COOK-TOP WITH IMPROVED
`TOUCH CONTROL
`
`RELATED APPLICATIONS
`
`This application is an improvement of co-pending
`U.S. patent application Ser. No. 819,164,filed July 26,
`1977, U.S. Pat. No. 4,169,222, and entitled “Induction
`Cook-Top System and Control” and U.S. patent appli-
`cation Ser. No. 819,169, filed July 26, 1977, U.S. Pat.
`No. 4,149,217, and entitled ““Touch Control Panel For
`Induction Heating Cook-Top.”
`TECHNICAL FIELD
`
`-
`
`This invention relates to. cook systems, and more
`particularly relates to an induction cook-top system.
`BACKGROUND ART
`
`30
`
`35
`
`The basic principles of induction heating have been
`known for quite some time. It has heretofore been
`knownto utilize power sources including rectifiers and
`inverters in order to drive an induction heating coil,
`thereby producing an alternating magnetic field which
`is coupled througha planar cooling surface to a cooking
`pan in order to provide cooking action. Examples of 25
`such previously developed induction cooking systems
`maybe found in U.S Pat. No. 3,637,970 issued to Cun-
`ningham on Jan. 25, 1972 and entitled “Induction Heat-
`ing Apparatus”; U.S. Pat. No. 3,697,716 issued to Korn-
`rumpfon Oct. 10, 1972 and entitled “Induction Cooking
`Power Converter with Improved Coil Position” and
`U.S. Pat. No. 3,823,297 issued to Cunningham onJuly 9,
`1974 and entitled “Load Controlled Induction Heat-
`ing”. It has also been known to utilize touch control
`devices to control the operation of such induction cook-
`ing devices.
`Previously developed induction cook-top devices
`have not provided adequate control systems for con-
`trolling the energization, deenergization. and variation
`of heating levels of induction heating coils. Lack of 40
`such control introduces unsafe operating conditions in
`the use of induction cook-top devices. For example, one
`such unsafe operating characteristic observed in prior
`art induction cook-top devices has been the inability to
`decrease a heating level of an induction heating coil
`when the induction heating coil is operating at a high
`level and the operator is in physical contact with the
`cooking pan or a utensil, such as a spoon, inside the
`cooking pan. The operator must therefore remember
`not to touch the cooking pan or a utensil in order to
`decrease the heating level or shut off an induction heat-
`ing coil. This operating requirement makes the opera-
`tion of induction cooking devices cumbersome and
`hazardous. Consequently, a need has arisen for an in-
`duction cook-top system which is economical to manu-
`facture and simple in operation, including touch con-
`trols that are accurate to safely control heating levels
`and energization of the system.
`DISCLOSURE OF THE INVENTION
`
`45
`
`50
`
`55
`
`60
`
`In accordance with the present invention, an induc-
`tion cook-top system is provided which substantially
`eliminates or reduces the problemsheretofore presentin
`prior multi-coil
`induction cook-tops utilizing touch
`control systems and visual displays.
`In accordancewith the present invention in an induc-
`tion cooking system a plurality of induction heating
`coils is provided. Circuitry is provided for electrically
`
`65
`
`1
`
`4,308,443
`
`2
`energizing the plurality of induction heating coils. Con-
`trols are provided for generating energization control
`signals. Circuitry is further provided being responsive
`to the energization control signals generated by the
`controls for generating energization signals. The energi-
`zation signal actuate and control the energization cir-
`cuitry to thereby vary the energization of the plurality
`of induction heating coils. Circuitry is provided for
`maintaining the controls operable when an operator is
`in contact with a pan disposed adjacentthe plurality of
`induction heatingcoils. Circuitry is further provided for
`reducing the voltagestress on the energization circuitry
`without changing the normal operating voltage levels
`of the energization circuitry.
`
`BRIEF DESCRIPTION OF DRAWINGS
`
`For a more complete understanding of the present
`invention and. for
`further objects and advantages
`thereof, reference is now made to the following De-
`tailed Description taken in conjunction with the accom-
`panying Drawings in which:
`FIG.1is a perspective top view ofan induction cook-
`top utilizing a touch control panel according to the
`present invention;
`FIG.2 is a top plan view of the touch control panel
`of the present invention shown in FIG. 1;
`FIG.3 is an electrical block diagram oftheelectrical
`control and logic circuitry of the touch control panel of
`the present invention;
`FIG.4 is a detailed schematic diagram of the touch
`padsand touchinputcircuit shownin the block diagram
`of FIG.3;
`FIG.5 is a detailed schematic diagram of the micro-
`processor and related circuitry shown in the block dia-
`gram of FIG.3;
`FIG. 6isa detailed schematic diagram of the pan and
`temperature sensors shown in the block diagram of
`FIG.3;
`FIG.7 is a detailed schematic diagramillustrating the
`powerdrivers shownin the block diagram of FIG.3;
`FIG.8 is a detailed schematic diagram of the inverter
`and induction heating coil circuitry shown in the block
`diagram of FIG.3;
`FIG.9 is a detailed schematic diagram illustrating the
`display and display drivers shownin the block diagram
`of FIG.3;
`FIG.10 is a software flow diagram of the basic sys-
`tem program for the microprocessor shownin the block
`diagram of FIG.3;
`w
`FIG. 11 is a software flow diagram of the. Timer
`Interrupt Routine;
`FIG. 12 is a software flow diagram of the Display
`Routine;
`FIG. 13 is a software flow diagram of the Gate Pulse
`Routine;
`FIG. 14 is a software flow diagram of the Clock
`Routine;
`FIG. 15 is a software flow diagram of the Display
`Digit Processing Routine;
`FIG. 16 is a software flow diagram of the Forty Sec-
`ond Turnoff Routine;
`FIG.17 is a software flow diagram of the Scan Lock
`and Unlock Pads Routine;
`FIG.18 is a software flow diagram of the Scan Down
`Pads Routine;
`FIG. 19 is a software flow diagram of the Scan Up
`Pads Routine;
`
`25
`
`25
`
`
`
`4,308,443
`
`3
`FIG. 20 is a software flow diagram of the Verify
`Selected Element Setting Routine;
`FIG. 21 is a software flow diagram of the Scan For
`Turnoff Commands Routine;
`FIG. 22 is a software flow diagram of the Clock
`Setting Routine;
`FIG.23 is a software flow diagram of the Flash Ac-
`tive Elements Routine; and
`FIG.24 is a software flow diagram of the External
`Interrupt Routine.
`DETAILED DESCRIPTION
`
`Referring to FIG. 1, a perspective top view of an
`induction cook-top surfaceis illustrated andis generally
`identified by the numeral 40. Cook-top surface 40 in-
`cludes a rectangular planar surface 42 having four cook-
`ing units or areas identified as A, B, C and D provided
`thereon. Cooking areas A and C are smaller than cook-
`ing areas B and D in orderto enable the accommodation
`of different size cooking pans. Surface 42 comprises a
`suitable ceramic or other material able to withstand
`high temperatures. Circular patterned indicia are
`formed in surface 42 to denote cooking areas A, B, C
`and D which are abovefour induction heating coils, not
`shown in FIG.1, and which are located beneath surface
`42.
`Surface 42 is maintained in place within a conven-
`tional kitchen counter 44 by a stainless steel mounting
`rim 46. A touch control panel of cook-top surface 49 is
`generally identified by the numeral 48 and includes
`touch control areas or pads 56 associated with each
`cooking area A-D. Touch control pads 56 provide con-
`trol of cooking areas A-D when the operator places a
`finger in contact with a designated surface of touch
`control pads 56. Touch control pads 56 illustrated in
`FIG. 1 comprise merely indicia formed ona glass plate
`57 and do not require physical depression by the opera-
`tor.
`Referring simultaneously to FIGS. 1 and 2, touch
`control panel 48 includes a LOCK TOUCH CON-
`TROL PAD 50 and an UNLOCK TOUCH CON-
`TROL PAD82 provided at the upper portion of touch
`control panel 48. The operation of LOCK TOUCH
`CONTROL PAD 50 and UNLOCK TOUCH CON-
`TROL PAD82 will be subsequently described. Associ-
`ated with each touch control pad 56 is a status display
`indicator 58, 58A-58D, to provide a visual indication
`when one or more cooking areas A-D are energized.
`Touch control panel 48 further includes a display gener-
`ally identified by the numeral 60 for alternately display-
`ing a visual indication of the desired powerto be deliv-
`ered to each of the cooking aread A-D. A representa-
`tion of the cooking powerdesired is displayed in display
`62 while the letter of the corresponding cooking area
`A-Dis illustrated in display 64.
`Touch control pads 56 each include a HI TOUCH
`CONTROL PAD 70, 70A-70D, and a LOW TOUCH
`CONTROLPAD72, 72A-72D, which maybe touched
`by the operator in order to set the heat indicator at a
`desired level. Touch control pads 56 further include an
`OFF TOUCH CONTROL PAD 174, 74A-74D, which
`may be touched by the operator in order to shut the
`associated cooking area A-D off. OFF TOUCH CON-
`TROL PAD74is disposed between HI TOUCH CON-
`TROL PAD 70 and LOW TOUCH CONTROL PAD
`72, such that the finger of an operator when in contact
`with OFF TOUCH CONTROL PAD74 bridges the
`area between HI TOUCH CONTROL PAD 70 and
`
`4
`LOW TOUCH CONTROLPAD72 to simultaneously
`touch both HI TOUCH CONTROL PAD 70 and
`LOW TOUCH CONTROLPAD72.
`In operation of induction cook-top surface 40, touch
`control pads 56 are initially locked in an off condition.
`The operator’s finger is, initially placed on the UN-
`LOCK TOUCH CONTROLPAD52 to enable opera-
`tion of touch control pads 56. The operator may then
`turn on a cooking area A-D by touching a HI TOUCH
`CONTROL PAD70. As soon as a Hi TOUCH CON-
`TROL PAD 70 is touched, the corresponding status
`display indicator 58 is illuminated to indicate that a
`cooking area has been selected.
`For example, if an operator desires to turn on cooking
`area A, HI TOUCH CONTROL PAD70Ais lightly
`touched with one finger by the operator. No pressure or
`depression by the finger of the operator is required. The
`display 64 displays the letter “A” to indicate that cook-
`ing area A is actuated. Display 62 will display in incre-
`ments often the relative cooking power delivered tothe
`cooking area A until 100 is reached. The percentage of
`the total power available for cooking area A will con-
`tinue to increase depending uponthe length oftime the
`operator’s finger is held on HI TOUCH CONTROL
`PAD 70A. until 100 is reached,asillustrated in FIG.2.
`The displayed power percentagerisesat a relatively fast
`rate when a HI TOUCH CONTROL PAD 70 is
`touched.
`To adjust the heat setting of a cooking area A-D,the
`LOW TOUCH CONTROLPADS72 are utilized. The
`amount of power applied to a cooking area A-D will
`decrease as long as the operator’s finger is held on LOW
`TOUCH CONTROL PAD 72A until display 62 indi-
`cates a 0. The rate of decrease in power to a cooking
`area is at a much slowerrate, in increments of one, than
`the increase rate of ten controlled by HI TOUCH
`CONTROL PAD 70, thus enabling a very accurate
`setting of the desired cooking powerlevel. If the opera-
`tor desires to again raise the temperature of cooking
`area A,
`it will be necessary to touch UNLOCK
`TOUCH CONTROLPAD52.
`The heat applied to each cooking area B-D may be
`regulated in a similar manner by touching touch control
`pads 56B-56Dofthe respective positions of touch con-
`trol panel 48.
`In order to turn a cooking unit completely off, the
`operator touches both the HI TOUCH CONTROL
`PAD 70 and the LOW TOUCH CONTROLPAD72
`for a cooking area A-D at the same time by placing a
`finger on each pad. The cooking area will be immedi-
`ately turned off and the status display indicator 58 will
`be extinguished. The display 64 will indicate the cook-
`ing area A-D previously actuated and display 62 will
`illustrate a 0. If none of the other cooking areas are on,
`display 60 will indicate the time of day.
`The use of LOCK TOUCH CONTROL PAD 50
`will cause all touch control pads 56 to be locked for a
`predetermined time, such as for five seconds, and each
`cooking area A-D will remain at its heat level setting at
`the time LOCK TOUCH CONTROL PAD 50 was
`touched. Thereafter,
`touching any of touch control
`pads 56 will have no effect on heating levels as long as
`induction cook-top surface 40 is in the locked mode. In
`order to restore operation from the locked modebefore
`the predetermined locked time has elapsed, the operator
`merely touches UNLOCK TOUCH CONTROL PAD
`52. UNLOCK. TOUCH CONTROL PAD 52 must be
`touched before any cooking area A-D can be turned on
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`35
`
`60
`
`65
`
`26
`
`26
`
`
`
`5
`or the power level setting of a cooking area A-D in-
`creased. While any of the cooking areas A-D are on,
`holding the operator’s finger on LOCK TOUCH CON-
`TROL PAD50 for a predetermined time will cause
`display 60 to indicate the time of day and touch control
`pads 56 will be inoperative. After a predetermined time
`after the operator’s finger is removed from LOCK
`TOUCH CONTROLPAD50,display 60 will revert to
`display the cooking area A-D in display 62 and the
`relative percentof heat applied to the cooking area A-D
`in display 62.
`Touch control panel 48 provides numerous safety
`features. Cook-top surface 40 is automatically lockedin
`the off position when powerisinitially applied to cook-
`top surface 40 and cook-top surface 40 cannot be oper-
`ated unless UNLOCK TOUCH CONTROLPAD52is
`touched. When cook-top surface 40 is turned on by
`holding of a finger on UNLOCK TOUCH CONTROL
`PAD 52, a cooking area A-D mustbe turned on within
`a predetermined time period, such as five seconds, or
`cook-top surface 40 and touch control pads 56 will
`automatically turn off. Each of cooking areas A-D may
`be turned off immediately by touching both HI and
`LOW TOUCH CONTROL PADS70 and 72 associ-
`ated with a cooking area A-D simultaneously. Due to
`the present inductive heating design, heat is immedi-
`ately extinguished and cook-top surface 40 does not
`retain heat which could causeserious burnsto the oper-
`ator.
`As will subsequently be described, cooking areas
`A-D will not operate unless a proper cooking pan is
`placed on the cooking area A-D. If the cooking area
`A-D is turned on with an improper pan or with no pan
`on the cooking area A-D,status display indicator 58 for
`that cooking area will flash for a predetermined time,
`such as forty seconds, or until the proper panis put on
`the cooking area A-D. During the flashing of status
`display indicator 58, no heat is generated from the cook-
`ing area A-D,If a pan is removed from the cooking area
`A-D during the cooking operation, the cooking area
`A-D will automatically terminate heating and thestatus
`display indicator 58 will flash. If the pan is returned to
`the cooking area A-D within a predetermined time
`period after removal, heating will resume in that cook-
`ing area. Otherwise, at the end of this predetermined
`time period, the cooking area A-D will return to the off
`state and status display indicator 58 will be extin-
`guished.
`Each cooking area A-D is equipped with a sensor
`which will turn the cooking area A-D off if a maximum
`level of operating temperature is exceeded, such as
`would occurif a cooking pan boiled dry.
`. Touch control panel 48 is constructed to minimize
`fabrication expense while providing ease of mainte-
`nance. Such a control panelis described in co-pending
`U.S. patent application Ser. No. 810,169 filed July 26,
`1977 and entitled “Touch Control Panel for Induction
`Heating Cook-top” and assigned to the assignee of the
`present invention. FIG.3 illustrates a block diagram of
`the electrical circuitry of the present touch control
`panel 48. Touch control panel 48 includes HI and LOW
`TOUCH CONTROL PADS70, 72, LOCK TOUCH
`CONTROL PAD 50 and UNLOCK TOUCH CON-
`TROL PAD52. Touch control pads 70, 72, 50 and 52
`are interconnected to touch input circuit 80 which
`senses that a touch control pad 70, 72, 50 and 52 has
`been touched by an operator. Touch input circuit 80
`senses which of touch control pads 70, 72, 50 and 52
`
`_ 0
`
`20
`
`25
`
`40
`
`45
`
`60
`
`65
`
`4,308,443
`
`6
`have been touched and provides energization contrél
`signals for cooking areas A-D to a microprocessorcir-
`cuit 82 via signal lines 84, 86, 88 and 90. Logic signals
`are also applied to microprocessorcircuit 82 from tem-
`perature sensors generally identified by the numeral 92
`via signal lines 94 and pan sensors generally identified
`by the numeral 96 via signal lines 98 located adjacent
`eachof the cooking areas A-D. Microprocessorcircuit
`82 also receives the input from an oscillator 100 via a
`signal line 102.
`Microprocessor circuit 82 generates energization
`signals for cooking areas A-D and applies these energi-
`zation signals via signal lines 110 to power drivers 112
`‘which generate selected electrical -power
`signals
`through transformers generally identified by the nu-
`meral 114to inverters 116. The outputs ofinverters 116
`are applied to the designated one of four induction
`heating coils generally identified by the numeral 118,
`one eachfor cooking areas A-D. Inductionheating coils
`118 are located beneath surface 42 of induction cook-
`top surface 40 in the vicinity of cooking areas A-D.
`ACvoltage is applied from a power source 122 to a
`DCpowersupply 124 whose outputis applied to invert-
`ers 116 in the manner to be subsequently described.
`Circuitry associated with powerdrivers 112 senses the
`zero voltage potential crossing of the AC voltage po-
`tential and generates the ZERO VOLTAGE CROSS-
`ING signal applied along signal
`line 126 to micro-
`processorcircuit 82. The function of the ZERO VOLT-
`AGE CROSSING signal will be subsequently de-
`scribed.
`An output of microprocessor circuit 82 is applied
`alongsignal line 128 to fan driver 130 for operating a fan
`132 located within the interior of induction cook-top
`surface 40 to provide cooling. Fan 132 operates when
`UNLOCK TOUCH CONTROLPAD 532is touched
`and is deactivated after all cooking areas A-D have
`been turned off.
`Microprocessor circuit 82 also generates via signal
`lines 134 output signals to display drivers 136 which
`generate signals via signal lines 138 to operate display
`60.
`AC poweris also applied to a power supply 140
`which supplies power to power drivers 112, micro-
`processor circuit 82, fan driver 130, display drivers 136
`and touch input circuit 80.
`Referring to FIG. 4, schematic circuitry correspond-
`ing to the touch input circuit 80 (FIG.3)is illustrated.
`Each touch control pad 70, 72, 50 and 52 operate in a
`similar manner and therefore only the circuitry associ-
`ated with UNLOCK TOUCH CONTROL PAD 52
`will be described herein. UNLOCK TOUCH CON-
`TROL PAD52 in conjunction.with copper areas 146
`and 148 located below touch control panel 48 (FIG. 1)
`is interconnected through a high impedanceresistive
`divider comprising resistors 150 and 154 to an inverter
`152. Resistor 150 may comprise, for example, a 9.1 meg-
`ohm resistance