United States Patent [19J
`Mazur et al.
`
`lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
`US005454591A
`5,454,591
`[11] Patent Number:
`[45] Date of Patent:
`Oct. 3, 1995
`
`[54] METHOD AND APPARATUS FOR SENSING A
`REARWARD FACING CHILD RESTRAINING
`SEAT
`
`[75]
`
`Inventors: Joseph F. Mazur, Washington; Brian
`K. Blackburn, Rochester; Scott B.
`Gentry, Romeo, all of Mich.
`
`[73] Assignee: TRW Vehicle Safety Systems Inc.,
`Lyndhurst, Ohio
`
`[21] Appl. No.: 263,191
`
`[22] Filed:
`
`Jun. 21, 1994
`
`Related U.S. Application Data
`
`[63] Continuation-in-part of Ser. No. 147,682, Mar. 11, 1993.
`Int. Cl.6
`..................................................... B60R 21132
`[51]
`[52] u.s. c1 •........................ 280n35; 2somo.1; IS0/273
`[58] Field of Search ................................ 2801735, 730 R;
`180/273; 340/436, 903; 307/9.1, 10.1; 364/424.05
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,172,684
`3,340,523
`3,992,028
`4,004,234
`4,063,230
`4,336,531
`4,502,042
`4,796,013
`4,804,859
`4,812,811
`4,973,944
`5,071,160
`5,074,583
`
`311965 Isaac ....................................... 280/235
`9/1967 Whitman ................................. 340/218
`1111976 Abe et al. . .......................... 2801728 R
`111977 Juvinal1 ....................................... 328/5
`12/1977 Purinton et al. ........................ 340/280
`6/1982 Kincaid ................................... 340/568
`2/1985 Wuhrl et al. ............................ 340/568
`111989 Yasuda et al. .......................... 340/562
`2/1989 Swart .................................. 307/105 B
`3/1989 Asbrink et al. ......................... 340/571
`1111990 Maletta ................................... 340/568
`12/1991 White et al ............................. 280/725
`12/1991 Fujita et al ............................. 2801735
`
`111992 Gill et al ................................. 340/572
`5,081,446
`5,118,134
`611992 Mattes et al ............................ 280/235
`5,161,820 1111992 Vollmer ................................... 2801730
`5,232,243
`811993 Blackburn et al. . .................... 2801732
`5,260,684 1111993 Metzmaker .......................... 340/457.1
`
`FOREIGN PATENT DOCUMENTS
`
`0458102
`3802159
`4212018
`4228624
`
`1111991
`8/1989
`10/1992
`10/1992
`
`European Pat. Off ..
`Germany ............................... 2801735
`Germany.
`Germany.
`
`OTHER PUBLICATIONS
`
`Research Disclosure #34457 "Air Bag Inhibitor for use with
`infant seat" Dec. 1992.
`An anonymous disclosure entitled "Air Bag Inhibitor for
`Use With Infant Seat", dated Dec. 1992.
`Automotive Occupant Sensor by Gencorp AeroJet.
`Research Disclosure, Nov. 1993, No. 355, Disclosure 35519.
`
`Primary Examiner-Mitchell J. Hill
`Assistant Examiner-Christopher P. Ellis
`Attorney, Agent, or Firm-Tarolli, Sundheim & Covell
`
`[57]
`
`ABSTRACT
`
`An apparatus (20) for preventing actuation of an air bag
`restraining device (25) of a vehicle includes a weight sensor
`(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
`
`34
`
`AIR BAG
`ACTUATION
`CIRCUIT
`
`24
`
`IPR2016-00291 - Ex. 1011
`Toyota Motor Corp., Petitioner
`
`1
`
`

`
`U.S. Patent
`
`Oct. 3, 1995
`
`Sheet 1 of 3
`
`5,454,591
`
`34
`
`CRASH
`SENSOR
`
`22
`
`AIR BAG
`ACTUATION
`CIRCUIT
`
`24
`
`Fig.1
`
`36
`
`68
`
`22
`
`CONTROLLER
`
`ENABLE
`
`+ BATTERY
`
`66
`
`SEAT BELT
`PAYOUT SENSOR
`
`70
`
`CRASH
`SENSOR
`
`72
`
`Fig.2
`
`2
`
`

`
`U.S. Patent
`
`Oct. 3, 1995
`
`Sheet 2 of 3
`
`5,454,591
`
`100
`
`DEACTIVATE
`INDICATOR
`~.....------' AND ENABLE
`AIR BAG
`SYSTEM
`
`N
`
`106
`
`114
`
`MEASURE DISTANCE
`FROM INSTRUMENT
`PANEL
`
`ACTUATE
`INDICATOR
`
`Fig.3
`
`114
`
`ACTUATE
`INDICATOR
`
`Fig.4
`
`1 10
`
`DEACTIVATE
`INDICATOR
`AND ENABLE
`AIR BAG
`SYSTEM
`
`3
`
`

`
`U.S. Patent
`
`Oct. 3, 1995
`
`Sheet 3 of 3
`
`5,454,591
`
`102
`
`100
`
`N
`
`110
`
`DEACTIVATE
`INDICATOR
`AND ENABLE
`AIR BAG SYSTEM
`
`MEASURE DISTANCE
`FROM
`INSTRUMENT
`PANEL
`
`114
`
`ACTUATE
`INDICATOR
`
`+ BATTERY
`
`L..----1 DISABLE
`AIR BAG
`
`36
`
`WEIGHT
`SENSOR
`
`82'-...:
`
`I
`
`Fig.S
`
`42
`
`DISTANCE
`SENSOR
`
`66
`
`SEAT BELT
`PAYOUT
`SESNOR
`
`Fig.6
`
`4
`
`

`
`5,454,591
`
`5
`
`1
`METHOD AND APPARATUS FOR SENSING A
`REARWARD FACING CHILD RESTRAINING
`SEAT
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`This is a continuation-in-part of U.S. patent application
`Ser. No. 147,682, 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 a rearward facing
`child restraining seat, preventing deployment of an air bag
`restraint.
`
`BACKGROUND OF THE INVENTION
`
`25
`
`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(cid:173)
`essary expense to repair of the vehicle.
`To prevent such unnecessary 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 35
`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.
`It 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 child's head and torso would
`not move relative to the child seat in the direction of vehicle
`travel.
`
`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(cid:173)
`ing seat is present on an associated occupant seat location.
`A presence sensing means senses the presence of a rearward
`10 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
`15 preferably includes an ultrasonic sensor. The presence sens(cid:173)
`ing means 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
`20 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(cid:173)
`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
`30 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 confirms
`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(cid:173)
`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
`40 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
`50 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.
`
`45
`
`SUMMARY OF THE INVENTION
`
`55
`
`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(cid:173)
`ing device of a vehicle. The apparatus includes presence
`sensing means for sensing the presence of a rearward facing 60
`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, 65
`and the actuatable occupant restraining device for prevent(cid:173)
`ing actuation of the actuatable occupant restraining device
`
`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(cid:173)
`nying drawings, wherein:
`FIG. 1 is a schematic of an apparatus for controlling an air
`
`5
`
`

`
`5,454,591
`
`3
`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
`
`5
`
`4
`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,
`1o over-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
`15 44 and, in tum, 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
`20 controller 22 indicative of the sensed distance. The control(cid:173)
`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/off switch may be used which
`switches state when the predetermined length of seat belt 48
`is extracted.
`Empirical testing has indicated that approximately 36
`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(cid:173)
`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 connected to con(cid:173)
`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
`60 22 indicative of the vehicle'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(cid:173)
`erometer signal and, in response to the signal, control the air
`bag actuation circuit 24. For example, the acceleration signal
`65 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
`
`30
`
`Referring to FIGS. 1 and 2, an apparatus 20, in accor(cid:173)
`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 sufficient amount of electric current for a sufficient
`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 and/or 25
`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 35
`that the controller can determine 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. 40
`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 45
`restraining seat in a rearward facing direction would weigh
`under 20 pounds. In the preferred embodiment, the prede(cid:173)
`termined 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--12lbs. plus a margin of safety. If 50
`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 55
`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.
`
`6
`
`

`
`5,454,591
`
`20
`
`35
`
`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 from 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 a 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(cid:173)
`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(cid:173)
`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 30
`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
`sensor 36 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 sensor 66 indicating
`a presence 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 50
`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(cid:173)
`pants that the air bag assembly 25 is disable.
`In accordance with yet another embodiment of the present
`invention, controller 22 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
`
`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(cid:173)
`cates that a rearward facing child seat is present and the
`5 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-
`10 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
`15 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
`affirmative, i.e., less than 40 lbs., the process proceeds to
`25 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(cid:173)
`tive of the measured distance. In step 108, controller 22
`determines whether the electrical signal provided by dis(cid:173)
`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 affirmative, 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(cid:173)
`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 affirmative, i.e., less than 40 lbs., the
`process proceeds to step 116.
`In step 116, seat belt payout sensor 66 provides controller
`60 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
`65 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
`
`40
`
`45
`
`55
`
`7
`
`

`
`5,454,591
`
`7
`74 is actuated to alert the vehicle occupants that the pas(cid:173)
`senger air bag restraint system is disabled. The process
`returns from step 114 to step 102. From a negative deter(cid:173)
`mination in either step 104 or step 118, the process proceeds
`to step 110 where the indicator 74 is deactuated (or remains 5
`deactuated) 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(cid:173)
`ously. Also, the order of steps 104 and 118 may be reversed.
`Referring to FIG. 5, yet another control process in accor(cid:173)
`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(cid:173)
`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(cid:173)
`mination in step 104 is affirmative, i.e., less than 40 lbs., the 20
`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- 25
`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 affir(cid:173)
`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 35
`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 40
`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 deactuated) and
`the air bag system is enabled (or remains enabled). The 45
`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 different 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 55
`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
`sufficient 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. 60
`Sensors 36, 42 and 66 provide electrical signals to controller
`22. The controller 22 determines whether there is a rearward
`facing child restraining seat 46 on occupant seat 40 as
`described above. If the determination is affirmative, control-
`ler 22 prevents actuation of the transistor 26 thereby pre- 65
`venting completion of the firing circuit even if the inertia
`switch 78 closes. If no rearward facing child seat is sensed,
`
`8
`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
`affirmatively to sense the presence of a rearward facing child
`restraining set. The weight sensor functions as a confirma(cid:173)
`tion sensor to confirm the presence of a child restraining seat
`10 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
`15 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(cid:173)
`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(cid:173)
`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
`30 occupant restraining device of a vehicle, said apparatus