United States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,454,591
`
`Mazur et al.
`
`[451 Date of Patent:
`
`Oct. 3, 1995
`
`I|||||llllllllll||||l||||l|l|l|||||l|1|||1||l|||||lllllllllllllllllllllll
`USOO5454591A
`
`[54] METHOD AND APPARATUS FOR SENSING A
`REARWARD FACING CHILD RESTRAINING
`SEAT
`
`Inventors:
`
`F. Mazur, Washington; Brian
`K. Blackburn, Rochester; Scott B.
`Gentry’ R°m°°’ an °f Mich‘
`[73] Assignee: (S)afety Systems Inc.,
`3'
`"
`
`5,081,446
`5,118,134
`5,161,820
`5,232,243
`
`1/1992 Gill et al. ................................ 340/572
`.. 280/235
`6/1992 Manes et al.
`11/1992 Vollmer ...........
`'... 280/730
`
`8/1993 Blackburn ctal.
`..
`280/732
`
`MCLZITIKKCT ..........................
`FOREIGN PATENT DOCUMENTS
`0458102
`11/1991
`E
`P1 011
`uropean a.
`13; gm
`4228624 10/1992 Germany.
`
`..
`
`280/735
`
`[21] AWL NW 253,191
`[22]
`Filed;
`Jam 21, 1994
`Rejaged U_s_ Appficgfion Data
`
`[63] Continuation-in-part of Ser. No. 147,682, Mar. 11, 1993.
`[51]
`Int. Cl.° ..................................................... B60R 21/32
`
`.. 280n3s; 280I730.1; 180/273
`[52]
`[58] Field of Search ................................ 280/735, 730 R;
`180/273; 340/436, 903; 307/9.1, 10.1; 304/424.05
`
`[56]
`
`References Cited
`vs. PATENT DOCUMENTS
`3/19155
`Isaac ....................................... 280/235
`3,172,684
`9/1967 Whitman . . .. . ..
`..... 340/218
`3,340,523
`11/ 1 976
`3,992,028
`. 280r728 R
`1/1977
`4,004,234
`--------- 328/5
`4,063,230 12/1977
`- 340030
`4,336,531
`6/1982
`343/
`4,502,042
`2/1985
`4 I
`4,796,013
`1/1989
`4,804,859
`2/1989
`_ 307/105 B
`4,812,811
`3/1989
`340,571
`4,973,944 ll/1990
`340/568
`5,071,160 12/1991
`280/725
`5,074,583 12/1991 Fujita et al.. I.......................... 280/735
`
`
`
`OTHER PUBLICATIONS
`1:2.-:2t1rsC‘1:1a?,iS[()31:(‘):Su]1‘;911154457 “AirBag Inhibitor for use with
`An anonymous disclosure entitled “Air Bag Inhibitor for
`Use With Infant Seat”. dated Dec. 1992.
`
`Automotive Occupant Sensor by Gcncorp Aero.1et.
`Research Dlsclosure’ Nov’ 1993’ No‘ 355’ Disclosure 35519‘
`P"i'fW')' Examir_zer—Mitc_hell J. Hill
`_
`Assistant Emmmer—§3lmsl0pher_P- Ellis _
`Attorney» A801!» 0' Fm"—T9I°111v Sundhelm & COW“
`57
`ABSTRACT
`
`1
`[
`A
`20 f
`'
`'
`f
`' h
`a‘§1.‘T’ai1‘1’fi1';"I1’Zv§c,’12é’§o‘E’§“v‘2‘§f1a”‘1i 31,?;‘h;‘:Zn;‘fi
`(36). a distance sensor (42), and a seat belt payout Sensor
`(66). A controller (22) is operatively connected to the
`sensors (36, 42, 66) and to the air bag restraining device
`(25). The controller (22) prevents actuation of the air bag
`when the sensors (36, 42, 66 ) sense a rearward facing child
`seat (46) on the occupant seat (40) by sensing a weight of an
`object less than a predetermined amount, a distance to an
`object on the seat (40) less than a predetermined amount,
`and a seat belt payout of greater than a predetermined
`amount-
`
`20 Claims, 3 Drawing Sheets
`
`CONTROLLER
`
`CIRCUIT
`
`AIR BAG
`ACTUATION
`
`lPR2016-01382 - Ex. 1011
`
`Toyota Motor Corp., Petitioner
`1
`
`

`
`U.S. Patent
`
`Oct. 3, 1995
`
`Sheet 1 of 3
`
`5,454,591
`
`34
`
`CRASH
`SENSOR
`
`20
`
`74-
`
`22
`
`44-
`
`45
`
`62
`
`‘__
`iCONTROLLER
`
`42
`
`40
`
`AIR BAG
`ACTUATION
`CIRCUIT
`
`
`
`
`
`WEIGHT
`SENSOR
`
`
`
`
`
`DISTANCE
`SENSOR
`
`66
`
`
`
`SEAT BELT
`PAYOUT SENSOR
`
`
`
`.34
`
`'
`
`

`
`U.S. Patent
`
`Oct. 3, 1995
`
`Sheet 2 of 3
`
`5,454,591
`
`1 10
`
`
`
`MBKSURE WEIGHT
`
`
`
`
`DEACTIVATE
`INDICATOR
`
`AND ENABLE
`AIR BAG
`
`
`SYSTEM
` IS
`
`WEIGHT
`LESS THAN
`40 LBS
`
`9
`
` MEASURE DISTANCE
`
`FROM INSTRUMENT
`
`PANEL
`
`114
`
`
`
`
`ACTUATE
`IN DI CATO R
` DISTANCE
`LESS THAN
`9 INCHES
`
`
`
`MEASURE WEIGHT
`
`
`
`
`
`114
`
`ACTUATE
`INDICATOR
`
`
`
`
`
`MEASURE SEAT
`BELT PAYOUT
`
`
`
`IS
`SEAT
`BELT PAYOUT
`GREATER THAN
`35 IN.
`'3
`
`
` 112
`
`Fig.4
`
`? 110
`DEACTIVATE
`
`
`|NmcA1'oR
`AND ENABLE
`NR BAG
`
`'5
`
`SYSTEM
`WEIGHT
`
`LESS THAN
`40 LBS
`?
`
`
`
`
`DISABLE
`AIR BAG
`
`F .3
`'9
`
`

`
`U.S. Patent
`
`Oct. 3, 1995
`
`Sheet 3 of 3
`
`5,454,591
`
`O
`
`1 1
`
`+ BATTERY
`
`5°
`
`8K
`
`78
`
`
`
`DISABLE
`AIR BAG
`
`Fig.5
`
`WEIGHT
`SENSOR
`
`
`
`
`
`
`4-2
`
`DISTANCE
`SENSOR
`
`66
`
`SEAT BELT
`PAYO UT
`SESNOR
`
`._,_ __I
`
`
`
`DEACTIVATE
`INDICATOR
`AND ENABLE
`AIR BAG SYSTEM
`
`MEASURE WEIGHT
`
`
`IS
`WEIGHT
`LESS THAN
`40 LBS
`?
`
`
`
`
`
`
`MEASURE DISTANCE
`FROM INSTRUMENT
`
`PANEL
`
`
`
`
`
`DISTANCE
`LESS THAN
`9 INCHES
`')
`
`ACTUATE
`INDICATOR
`
`
`
`MHSURE SEAT
`BELT PAYOUT
`
`
`
`IS
`sEAT
`BELT PAYOUT
`GREATER THAN
`35 IN.
`7
`
`
`
`35
`
`

`
`5,454,591
`
`1
`METHOD AND APPARATUS FOR SENSING A
`REARWARD FACING CHILD RESTRAINING
`SEAT
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`5
`
`This is a continuation-in-pan of U.S. patent application
`Ser. No. l47,682, filed Nov. 3, 1993, pending to Blackburn,
`et al., for “Method and Apparatus for Sensing a Rearward
`Facing Child Seat” and assigned to TRW Vehicle Safety
`Systems Inc.
`
`TECHNICAL FIELD
`
`The present invention is directed to a vehicle occupant
`restraint system. The invention is specifically directed to a
`method and apparatus for sensing a rearward facing child
`restraining seat and, in response to sensing arearward facing
`child restraining seat, preventing deployment of an air bag
`restraint.
`
`20
`
`BACKGROUND OF THE INVENTION
`
`Air bag restraint systems for vehicles are well known in
`the art. It is also known to prevent deployment of an air bag
`during a vehicle crash when the air bag is associated with a
`seat location that is unoccupied. Deployment of an air bag
`associated with an unoccupied seat location (typically the
`passenger seat location) during a vehicle crash adds unnec-
`essary expense to repair of the vehicle.
`To prevent such urmecessary deployment of an air bag at
`an unoccupied seat location, sensors are provided to detect
`the presence of an occupant on the vehicle seat. These
`sensors include pressure sensing switches located in the seat
`cushion or infrared or ultrasonic sensors located in the
`
`vehicle dashboard or instrument panel. If no occupant is
`detected as being present on the seat, deployment of an
`associated air bag during a crash condition is prevented
`through an appropriate control arrangement
`11 is also desirable to prevent actuation of an air bag
`restraint system when a child restraining seat is secured and
`positioned in a rearward facing orientation on an associated
`seat location. When a rearward facing child seat is secured
`to a vehicle seat, deployment of an associated air bag during
`a vehicle crash condition would not provide the child with
`additional protection since the ch.ild’s head and torso would
`not move relative to the child seat in the direction of vehicle
`travel.
`
`SUMMARY OF THE INVENTION
`
`The present invention provides a method and apparatus
`for sensing presence and orientation of a child restraining
`seat and preventing deployment of an associated air bag
`during a vehicle crash condition if the rearward facing child
`seat is sensed as being present.
`In accordance with the invention, an apparatus is provided
`for preventing actuation of an actuatable occupant restrain-
`ing device of a vehicle. The apparatus includes presence
`sensing means for sensing the presence of a rearward facing
`child restraining seat on an occupant seat of the vehicle. The
`apparatus further includes confirmation sensing means for
`confirming the presence of the child restraining seat on the
`occupant seat. Control means is operatively connected to the
`presence sensing means. the confirmation sensing means,
`and the actuatable occupant restraining device for prevent-
`ing actuation of the actuatable occupant restraining device
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`
`when both (i) the presence sensing means senses a rearward
`facing child restraining seat on the occupant seat and (ii) the
`confirmation sensing means confirms the presence of the
`child restraining seat on the occupant seat.
`In accordance with a preferred embodiment of the present
`invention, an apparatus is provided for preventing actuation
`of an air bag restraint when a rearward facing child restrain-
`ing seat is present on an associated occupant seat location.
`A presence sensing means senses the presence of a rearward
`facing child restraining seat on the occupant seat. The
`presence sensing means includes a distance sensor mounted
`in the instrument panel for providing a signal having a value
`indicative of the distance between the distance sensor and an
`
`object in front of the distance sensor. The distance sensor
`preferably includes an ultrasonic sensor. The presence sens-
`ing mcans further includes a seat belt payout sensor for
`providing a signal indicative of the amount of seat belt
`extracted from a seat belt retractor. An amount of seat belt
`greater than a threshold amount needs to be extracted to
`secure a rearward facing child seat to the occupant seat. The
`apparatus further comprises confirmation sensing means for
`confirming the presence of a child restraining seat on an
`occupant seat of a vehicle and for providing a confirmation
`signal indicative thereof. Preferably, the confirmation sens-
`ing means includes a weight sensor for providing the con-
`firmation signal when weight on the occupant seat is less
`than a threshold amount. Control means is operatively
`connected to the distance sensor, the belt payout sensor, the
`weight sensor, and to the actuatable occupant restraining
`device for preventing actuation of the actuatable occupant
`restraining device when both the distance sensor and belt
`payout sensor indicates a rearward facing child restraining
`seat is on the occupant seat and the weight sensor confinns
`that the child restraining seat is present on the occupant seat.
`Also in accordance with the present invention, a method
`is provided for preventing actuation of an actuatable occu-
`pant restraint device of a vehicle. The method comprises the
`steps of sensing the presence of a child restraining seat on an
`associated occupant seat and confirming the presence of the
`child restraining seat on the occupant seat. Actuation of the
`actuatable occupant restraining device is prevented when the
`rearward facing child restraining seat is sensed as being
`present on the occupant seat and it is confirmed that the child
`restraining seat is on the occupant seat.
`In accordance with a preferred embodiment of the present
`invention, a method is provided for preventing actuation of
`an air bag restraint when a rearward facing child restraining
`seat is present _on an associated occupant seat location. The
`method includes the steps of sensing the distance between
`the vehicle instrument panel and an object on an occupant
`seat of a vehicle. sensing seat belt payout, and sensing if
`weight on the occupant seat is less than a threshold value.
`The method further comprises the step of preventing actua-
`tion of the actuatable occupant restraining device when the
`sensed distance and sensed belt payout indicate a rearward
`facing child restraining seat is on the occupant seat and the
`sensed weight confirms a child restraining seat is on the
`occupant seat.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other features of the present invention
`will become apparent to those skilled in the art to which the
`present invention relates upon consideration of the following
`description of the invention with reference to the accompa~
`nying drawings, wherein:
`FIG. 1 is a schematic of an apparatus for controlling an air
`
`

`
`3
`
`4
`
`5,454,591
`
`bag restraint in accordance with the present invention;
`FIG. 2 is a schematic block diagram showing a portion of
`the circuitry of FIG. 1;
`FIGS. 3-5 are flow charts depicting the control process
`followed by the controller of FIG. 1; and
`FIG. 6 is a schematic block diagram showing another
`embodiment of a portion of the circuitry of FIG. 1.
`
`DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`Referring to FIGS. 1 and 2, an apparatus 20, in accor-
`dance with the present invention, includes a controller 22
`operatively connected to an air bag actuation circuit 24.
`Actuation circuit 24 is operatively coupled to an air bag
`assembly 25. The air bag actuation circuit 24 includes a
`transistor 26 that is electrically connected in series between
`a squib 28 and a source of electrical energy. Controller 22 is
`controllably connected to the base of transistor 26. When
`controller 22 actuates transistor 26 so as to turn the transistor
`“ON”, a suflicient amount of electric current for a sufiicient
`time duration passes through squib 28 to ignite the squib.
`Squib 28 is operatively coupled to a source of inflation
`fluid 30, such as an ignitable gas generating material andlor
`a container of pressurized gas. The inflator 30 is operatively
`coupled to an air bag 32. Upon ignition of the squib 28,
`inflation fluid from the inflator 30 inflates air bag 32 to its
`operative restraining position.
`The apparatus 20 further includes a crash sensor 34
`operatively connected to controller 22. A weight sensor 36
`is operatively mounted in a seat cushion 38 of an occupant
`seat 40 and is electrically connected to controller 22. The
`weight sensor 36 provides a signal to the controller 22 so
`that the controller can detennine whether an object on the
`occupant seat 40 weighs more than a predetermined value.
`Weight sensor 36 may be any one of several known in the
`art For example, a weight sensor of the type described in
`U.S. Pat. No. 5,232,243 to Blackburn et al. may be used.
`Alternatively, a switch which opens or closes in response to
`applied weight greater than the predetermined value may
`also be used.
`
`A typical child restraining seat weighs approximately
`10-12 pounds. A small child that would be placed in such a
`restraining seat in a rearward facing direction would weigh
`under 20 pounds. In the preferred embodiment, the prede-
`terrnined threshold weight value is 40 lbs. to account for the
`presence of a child under 20 lbs. plus the weight of a child
`restraint seat weighing 10-12 lbs. plus a margin of safety. If
`an object on the seat cushion 38 weighs more than 40 lbs.,
`it is assumed that the object can not be a rearward facing
`child seat. If the weight sensor 36 is a switch, it is arranged
`to provide one signal if an object weighing more than 40 lbs.
`is on the seat cushion 38. The weight sensor 36 provides a
`second signal when no object weighing more than 40 lbs. is
`on the seat cushion 38.
`
`A distance sensor 42 is mounted in instrument panel/
`dashboard 44 of the vehicle and is electrically connected to
`controller 22. The distance sensor 42 provides a signal
`indicative of the distance between the distance sensor 42 and
`an object located on the occupant seat 40 in operative line
`with the distance sensor 42. Distance sensor 42 may be any
`one of several types known in the art. For example, in
`accordance with a preferred embodiment, an ultrasonic
`sensor is used. Other sensors that could be used include
`active or passive infrared sensors.
`
`20
`
`30
`
`40
`
`45
`
`55
`
`65
`
`A child restraining seat 46 is secured to the seat 40 in a
`rearward facing direction with a seat belt 48 that is attached
`to the vehicle floor 50 on one side of the seat 40 through a
`mounting assembly 52 and buckle 54 as is well known in the
`art. The seat belt 48 passes through a belt holder 56 of the
`child restraining seat 46 and is secured to the vehicle floor
`50 on the other side of the seat 40 through a seat belt
`retractor assembly 58, also well known in the art A child 60
`is secured in the child restraining seat 46 using a three-point,
`ovcr—both-shoulders harness restraint 62 that is typical for
`child restraining seats.
`When a child restraining seat 46 is secured in a rearward
`facing orientation on occupant seat 40. the back 64 of child
`restraining seat 46 is closer to instrument panel/dashboard
`44 and,
`in turn,
`to the sensor 42, than when the child
`restraining seat 46 is in a forward facing orientation. The
`back portion 64 of a rearward facing child seat is typically
`less than 9 inches from the sensor 42. In the preferred
`embodiment, the distance sensor 42 provides a signal to
`controller 22 indicative of the sensed distance. The control-
`ler 22 determines if the distance is less than or equal to 9 in.
`from the distance sensor 42.
`
`A seat belt payout sensor 66 is located in seat belt retractor
`58 and is electrically connected to controller 22. Seat belt
`retractor 58 is attached to vehicle floor 50. Seat belt payout
`sensor 66 measures the length of seat belt 48 extracted from
`or paid out from seat belt retractor 58 and provides an
`electrical signal indicative of the length of seat belt 48 paid
`out. When a child restraining seat is secured in a rearward
`facing direction, a belt payout equal to or greater than a
`predetermined amount occurs. Therefore, if the belt payout
`indication is greater than the predetermined amount, it is
`assumed that a rearward facing child seat is present. Seat
`belt payout sensor 66 may be any one of several types
`including a potentiometer that provides an electrical signal
`having a value functionally related to the length of seat belt
`48 extracted. A threshold on/ofi” switch may be used which
`switches state when the predetermined length of seat belt 48
`is extracted.
`
`testing has indicated that approximately 36
`Empirical
`inches of seat belt is needed to secure a rearward facing child
`seat on the occupant seat 40. It takes approximately 30
`inches of belt to secure a forward facing child seat. There-
`fore,
`the belt payout
`threshold value is set
`internal
`to
`controller 22 at 35 inches.
`
`Controller 22 includes both an enable function 68 and an
`evaluation function 70. When both functions provide a
`digital HIGH signal, controller 22 actuates circuit 24 to
`energize the squib 28.
`Referring to FIGS. 1 & 2, the evaluation function 70 and
`the enable function 68 of controller 22 will be better
`appreciated A vehicle crash sensor 34 is operatively
`mounted to the vehicle and electrically cormected to con-
`troller 22. Crash sensor 34 may be any one of several known
`crash sensors, including an inertia switch or an accelerom-
`eter. In a preferred embodiment,
`the crash sensor is an
`accelerometer.
`'
`
`Crash sensor 34 provides an electrical signal to controller
`22 indicative of the vehiele’s crash acceleration. Those
`skilled in the art will appreciate that controller 22 may use
`any one of several known algorithms to analyze the accel-
`erometer signal and, in response to the signal, control the air
`bag actuation circuit 24. For example, the acceleration signal
`may be integrated to determine a crash velocity value. If the
`crash velocity exceeds a predetermined crash velocity
`threshold value, evaluation function 70 provides a digital
`
`

`
`5,454,591
`
`5
`HIGH signal to one input of an ANDING function 72 of
`controller 22.
`
`Sensors 36, 42, 66 provide electrical signals to controller
`22. The electrical signals front sensors 36, 42, 66 are used by
`controller 22 to determine the presence of a rearward facing
`child seat 46 on occupant seat 40. If controller 22 determines
`from the sensor signals that a rearward facing child seat is
`present, the enable function 68 outputs 21 LOW signal to a
`second input of ANDING function 72. This LOW output
`from the enable function 68 disables air bag actuation circuit
`24. The enable function 68 normally provides a digital
`HIGH signal referred to herein as the enable function’s
`default condition.
`
`When controller 22 receives appropriate signals from both
`(i) distance sensor 42 indicating the presence of a rearward
`facing child restraining seat on occupant seat 40, and (ii)
`weight sensor 36 confirming the presence of a child restrain-
`ing seat on occupant seat 40, the controller decides that a
`rearward facing child seat is present. The controller makes
`this decision by comparing the measured distance and
`weight against associated threshold values. When the dis-
`tance sensor 42 indicates that a rearward facing child
`restraining seat is present and the weight sensor 36 confirms
`the presence of a child restraining seat, the enable function
`68 provides a digital LOW signal. The LOW signal from
`enable function 68 prevents air bag actuation circuit 24 from
`energizing squib 28 since the output of the ANDING func-
`tion 72 will be a LOW. When the air bag system is disabled,
`the controller 22 provides an electric signal to an indicator
`74 on the instrument panel/dashboard 44 to alert the vehicle
`occupants that the air bag assembly 25 is disabled.
`In accordance with another embodiment of the present
`invention, controller 22 monitors the signal from weight
`sensor36 as described above. As mentioned, seat belt payout
`sensor 66 provides an electrical signal
`to controller 22
`indicating the length of seat belt 48 extracted from seat belt
`retractor assembly 58. Controller 22 determines whether the
`length of seat belt 48 extended exceeds the predetermined
`length threshold value which would indicate the presence of
`a rearward facing child restraining seat 46. When controller
`22 receives signals from both (i) payout sensor66 indicating
`apresence of a rearward facing child restraining seat 46 and,
`(ii) weight sensor 36 confirming the presence of a child
`restraining seat 46 on occupant seat 40,
`the controller
`decides that a rearward facing child seat is present. The
`controller accomplishes this by comparing measured belt
`payout and weight against associated limits. When the
`payout sensor 66 indicates that a rearward facing child
`restraining seat is present and the weight sensor 36 confirms
`the presence of a child restraining seat, the enable function
`68 provides a digital LOW signal. The LOW signal from
`enable function 68 prevents air bag actuation circuit 24 from
`energizing squib 28 since the output of ANDING function
`72 will be LOW. When the air bag is disabled, the controller
`22 provides an electric signal to an indicator 74 mounted in
`the instrument panel/dashboard 44 to alert the vehicle occu-
`pants that the air bag assembly 25 is disable.
`In accordance with yet another embodiment of the present
`invention, controller 2 monitors signals from weight sensor
`36, distance sensor 42, and seat belt payout sensor 66.
`When controller 22 receives appropriate signals from (i)
`payout sensor 66 indicating a presence of a rearward facing
`child seat, (ii) distance sensor 42 indicating the presence of
`rearward facing child restraining seat 46, and (iii) weight
`sensor 36 confirming the presence of a child restraining seat
`46 on occupant seat 40, the controller decides that a child
`
`I5
`
`20
`
`25
`
`30
`
`35
`
`40
`
`50
`
`60
`
`65
`
`6
`restraining seat is present. The controller accomplishes this
`by comparing measured belt payout, distance, and weight
`against associated limits. When the payout sensor 66 indi-
`cates that a rearward facing child seat is present and the
`distance sensor 42 indicates that a rearward facing child
`restraining seat is present and the weight sensor 36 confirms
`the presence of a child restraining seat, the enable function
`68 provides a digital LOW signal to ANDING function 72.
`The LOW signal from enable function 68 prevents energi-
`zation of squib 28. When the air bag is disabled,
`the
`controller 22 provides an electric signal to indicator 74 to
`alert the vehicle occupants that the air bag assembly 25 is
`disabled.
`
`Referring to FIG. 3, the control process of the present
`invention will be better appreciated. In step 100. the control
`process is initialized by the controller 22 setting the enable
`function 68 to a default state providing a digital HIGH signal
`so as to enable the air bag system and deactuating indicator
`74. In step 102, weight sensor 36 measures the weight of an
`object on occupant seat 40 and provides an electric signal
`indicative of weight to controller 22. The process proceeds
`to step 104 where controller 22 determines whether the
`electrical signal provided by weight sensor 36 indicates a
`weight less than 40 lbs. If the determination in step 104 is
`aflirmative, i.e., less than 40 lbs., the process proceeds to
`step 106.
`In step 106, the distance sensor 42 measures the distance
`between an object on occupant seat 40 and distance sensor
`42 and provides an electrical signal to controller 22 indica-
`tive of the measured distance. In step 108, controller 22
`determines whether the electrical signal provided by dis-
`tance sensor 42 indicates an object is at a distance of less
`than nine inches from sensor 42. If the determination in step
`108 is aflirmative, the process proceeds to step 112 where the
`controller 22 disables the air bag actuation circuit 24. The
`process then proceeds to step 114 where indicator 74 is
`actuated to alert the vehicle occupants that the passenger air
`bag restraint system is disabled. From step 114, the process
`returns to step 102. From a negative determination in either
`step 104 or in step 108, the process proceeds to step 110
`where the indicator 60 is deactuated (or remains deactuated)
`and the air bag system is enabled (or remains enabled). From
`step 110, the process returns to step 102. It will be appre-
`ciated by those skilled in the art that the control process
`repeats and evaluates the sensor signals continuously. Also,
`the order of steps 104 and 108 may be reversed.
`FIG. 4 illustrates another control process in accordance
`with the present invention. As in the control process of FIG.
`3, in step 100, the enable function 68 is set to its default state
`providing a digital HIGH signal to enable the air bag system
`and the indicator 74 is deactuated. In step 102. weight sensor
`36 measures the weight of an object on occupant seat 40 and
`provides an electric signal indicative of weight to controller
`22. The process proceeds to step 104 where controller 22
`determines whether the electrical signal provided by weight
`sensor 36 indicates a weight less than 40 lbs. If the deter-
`mination in step 104 is affirrnative, i.e., less than 40 lbs., the
`process proceeds to step 116.
`In step 116, seat belt payout sensor 66 provides controller
`22 with an electrical signal indicating the length of seat belt
`48 extended from seat belt retractor assembly 58. The
`process then proceeds to step 118 where controller 22
`determines whether the length of seat belt 48 extracted is
`greater than 35 inches. If the determination in step 118 is
`affirmative,
`the process proceeds to step 112 where the
`controller 22 disables the air bag actuation circuit 24. The
`process proceeds from step 112 to step 114 where indicator
`
`

`
`7
`
`8
`
`5,454,591
`
`74 is actuated to alert the vehicle occupants that the pas-
`senger air bag restraint system is disabled. The process
`returns from step 114 to step 102. From a negative deter-
`mination in either step 104 or step 118, the process proceeds
`to step 110 where the indicator 74 is deactuated (or remains
`deactuatcd) and the air bag system is enabled (or remains
`enabled). From step 110, the process returns to step 102. It
`will be appreciated by those skilled in the art that the control
`process repeats and evaluates the sensor signals continu-
`ously. Also, the order of steps 104 and 118 may be reversed.
`Referring to FIG. 5, yet another control process in accor-
`dance with the present invention is shown. As above, in step
`100,
`the enable function 68 is set
`to its default state
`providing a digital HIGH signal to enable the air bag system
`and indicator 74 is deactuated. In step 102, weight sensor 36
`measures the weight of an object on occupant seat 40 and
`provides an electrical signal indicative of weight to control-
`ler 22. The process proceeds to step 104 where controller 22
`determines whether the electrical signal provided by weight
`sensor 36 indicates a weight less than 40 lbs. If the deter-
`mination in step 104 is aflirmative, i.e., less than 40 lbs., the
`process proceeds to step 106.
`In step 106, the distance sensor 42 measures the distance
`between an object on occupant seat 40 and distance sensor
`42. An electrical signal is provided to controller 22 indica-
`tive of the measured distance. The process thus proceeds to
`step 108. In step 108, controller 22 determines whether the
`electrical signal provided by distance sensor 42 indicates a
`distance less than nine inches. If the determination is aflir-
`mative, the process proceeds to step 116.
`In step 116, seat belt payout sensor 66 provides controller
`22 with an electrical signal indicating the length of seat belt
`48 extended from seat belt retractor assembly 58. The
`process then proceeds to step 118 where controller 22
`determines whether the length of seat belt 48 extended is
`greater than 35 inches. If the determination is affirmative, the
`process proceeds to step 112 where the controller 22 disables
`the air bag actuation circuit 24. The process then proceeds
`from step 112 to step 114 where indicator 74 is actuated to
`alert
`the vehicle occupants that
`the passenger air bag
`restraint system is disabled. The process returns from step
`114 to step 102. From a negative determination in any of
`steps 104, 108. or 118, the process proceeds to step 110
`where indicator 74 is deactuated (or remains dcactuated) and
`the air bag system is enabled (or remains enabled). The
`process returns from step 110 to step 102. It will be
`appreciated by those skilled in the art that the control process
`repeats and evaluates the sensor signals continuously. Also,
`the order of steps 104, 108 and 118 may be difierent from
`that shown and described.
`
`Referring to FIG. 6, an alternate embodiment of the
`present invention is shown. The squib 28 is connected in
`series with transistor 26, an inertia switch 78, and diode 80
`across a source of electrical energy. This forms a series
`connected firing circuit. A storage capacitor 82 is connected
`to the cathode side of diode 80, as is known in the art, to
`provide a back-up energy source. During a crash event of
`suflicicnt intensity, inertia switch 78 will close. The control-
`ler 22 is operatively connected to weight sensor 36, distance
`sensor 42 and seat belt payout sensor 66 as described above.
`Sensors 36, 42 and 66 provide electrical signals to controller
`22. The controller 22 determines whether there is arearward
`facing child restraining seat 46 on occupant seat 40 as
`described above. If the determination is aflirmative, control-
`ler 22 prevents actuation of the transistor 26 thereby pre-
`venting completion of the firing circuit even if the inertia
`switch 78 closes. If no rearward facing child seat is sensed,
`
`10
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`20
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`30
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`45
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`50
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`55
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`65
`
`the controller 22 provides a control signal to turn transistor
`26 ON. When transistor 26 is ON and inertia switch 78
`closes, the squib 28 is ignited resulting in deployment of the
`air bag.
`It should be appreciated by those skilled in the art that the
`distance sensor 42 and/or the belt payout sensor 66 function
`afiirrnatively to sense the presence of a rearward facing child
`restraining set. The weight sensor functions as a confirma-
`tion sensor to confirm the presence of a child restraining seat
`on the occupant seat. Assume an occupant (an adult) is on
`the occupant seat holding a newspaper within 9 inches of the
`distance sensor. Since the adult would weigh more than 40
`lbs. the weight sensor would not provide the confirmation
`needed to indicate a rearward facing child seat Assume that
`a very large adult is on the occupant seat and extends the seat
`belt 35 inches. The large adult would weigh more than 40
`lbs. Therefore, the weight sensor would not provide the
`confirmation needed to disable the air bag system.
`From the above description of the invention, those skilled
`in the art will perceive improvements, changes and modi-
`fications. For example, the threshold weight value of 40 lbs.
`and the threshold sensed distance value of 9 in. could vary
`depending upon the requirements of the vehicle manufac-
`turer and the configuration of the interior of the particular
`vehicle in which the invention is used. Such improvements,
`changes and modifications are intended to be covered by the
`appended claims.
`Having described the invention, the following is claimed:
`1. An apparatus for preventing actuation of an actuatable
`occupant restraining device of a vehicle, said apparatus
`comprising:
`presence sensing means for sensing the presence of a
`rearward facing child restraining seat on an occupant
`seat of the vehicle and for providing a presence signal
`indicative thereof;
`
`confirmation sensing means for confirming the presence
`of said child restraining seat on said occupant seat and
`for providing a confirmation signal indicative thereof;
`and
`
`control means operatively connected to said presence
`sensing means, said confirmation sensing means, and to
`said actuatable occupant restraining device for prevent-
`ing actuation of said actuatable occupant restraining
`device when both said presence signal indicates said
`rearward facing child restraining seat is on said occu-
`pant seat and said signal from said confirmation sensing
`means confirms said child restraining seat is on said
`occupant seat.
`2. The apparatus of claim 1 wherein said confirmation
`sensing means includes weight sensing means for sensing
`weight on said occupant seat and for providing said confir-
`mation signal indicative of said child restraining seat being
`on said occupant seat when the weight on said occupant seat
`is less than a weight thresh