FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
An Improved Portable Apparatus For Measurement Of Backset Of A Seat Head Restraint And Method Of Measurement Thereof


APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

INVENTOR
Vinayak S Gogate
An Indian National
of TATA MOTORS LIMITED an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India


FIELD OF INVENTION
This invention relates to an apparatus for measurement of backset of a seat head restraint.
BACKGROUND OF INVENTION
Whiplash injuries are one of the significant injuries in rear impact crashes. In a whiplash, there is an unsynchronized movement of head with respect to the chest. Such an excessive movement results into serious injuries to the neck which needs a long term medical treatment. The vehicle seats are provided with head restraints, also known as head rests, to provide adequate support to the head to minimize the relative movement of the head & reduce the possibility of serious injuries to the neck. Various parameters have been identified for assessment of effectiveness of the head restraint to reduce the possibility of whiplash injuries. One of such parameter is known as backset. It is the gap between head and head restraint.
Presently the backset measurements are performed by 2 methods. In one case a Head Restraint Measurement Device (HRMD), attached to an H point machine, is used. In another method an apparatus consisting of 2 pivoted arms & a backset measurement scale is used.
Following are few technical terms required to understand the technicality of the concept in the subsequent document -
• Anthropometry - these are the measurement of size & mass of human objects,
• H point - it is known as Hip pivot point. A human being can be considered to have pivoted against an imaginary point between the upper torso & lower legs. Each seat is characterized by its H point to define occupant position in a seat.

• R point - it is known as seat reference point. The vehicle layouting
is prepared with reference to the R point. The seats are positioned in a
vehicle in such a way that the seat H point coincides with R point.
a) H point machine with an HRMD - in this method an H point machine, used to
establish H- point of a seat, is positioned on a seat and HRMD is attached to this
machine to measure the backset. This method is not very convenient for the
following reasons -
• The weight of H point machine is 76 kg and therefore it is very cumbersome to handle & operate.
• The machine does not contain any adjustment for torso height or head height. Therefore it can not be used for a data generation for variable anthropometry.
b) portable apparatus for backset measurement - this apparatus consists of 2
pivoted arms & a measuring probe for the backset. However the length of the
arms is fixed. During measurement the apparatus is positioned on the seat such
that the lower pivot is aligned with the seat H point or R point whichever is the
reference of interest. This apparatus have following disadvantages :
• Pivoted arms being of fixed length, the apparatus is not suitable for the backset measurements for different anthropometries.
• Also the apparatus does not have a base for positioning on the seat and therefore it requires an auxiliary set up for positioning of the apparatus.
OBJECTS OF INVENTION
The main objective of the present invention is to provide an improved portable apparatus to measure backset of a seat head restraint wherein the positioning arms have adjustable lengths.

Another objective of the present invention is to provide an improved portable apparatus to measure backset of a seat head restraint which has a base for easy positioning on a seat cushion structure.
Yet another objective of the present invention is to provide a portable apparatus to measure backset of a seat head restraint which is simple in construction, lightweight & portable.
STATEMENT OF INVENTION
Accordingly the present invention discloses an improved portable apparatus for measurement of backset of a seat head restraint comprising
at least one position bracket configured for positioning it on the seat structure;
at least two arms configuring lower arm and upper arm with adjustable lengths and inclinations, pivotally connected to each other of which said lower arm configured to be pivotally connected to said position bracket;
plurality of locking mechanisms for fixing the set lengths and inclinations of said arms;
at least one sliding probe provided through the top block of upper arm to measure the backset of the seat head restraint;
plurality of measuring scales for measuring various lengths and inclinations;
at least one level indicator is provided on the top block of said upper arm to facilitate alignment of said apparatus with vertical axis.
BRIEF DESCRIPTION OF DRAWINGS
According to the present invention
Figure - 01 shows side view of an improved portable apparatus for measurement of backset of a seat head restraint, in accordance with this invention

Figure - 02 shows the front view of the said improved portable apparatus in
accordance with this invention, Figure - 03 & 04 show isometric views of the said improved portable apparatus in
accordance with this invention. Figure - 05 shows the details of the locking arrangement at pivot PI location. Figure - 06 shows the details of the locking arrangement at pivot P2 location. Figure - 07 shows sectional view of the positioning bracket at pivot PI Figure - 08 shows installation of the said portable apparatus on a seat for the measurement of the backset.
BRIEF DESCRIPTION OF INVENTION
An portable apparatus for measurement of back set of a seat head restraint consisting of a positioning bracket, two arms with adjustable lengths & inclinations, locking mechanisms for setting the length & inclinations of these arms, a measuring probe with sector to position against the head restraint & scale integrated to the measuring probe to measure the backset, a spirit level for easy alignment of the upper arm with the vertical.
DETAILED DESCRIPTION OF INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.
Now referring to fig 01 to 04, a portable apparatus for measurement of backset of an automotive seat consist of an L shaped positioning bracket (1), lower arm (2), upper arm (3), sliding probe (4). The said lower arm is pivoted at the said positioning bracket at pivot PI through pivot block (5). The said lower & upper

arms are pivoted at pivot P2. The said upper arm is provided with a sliding probe (4) to measure the backset of a seat head restraint.
The said L shaped positioning bracket consists of a horizontal part (1.1) & a vertical part (1.2). During backset measurements on a seat the said positioning bracket is positioned on seat structure on the said horizontal face. The said horizontal & vertical parts are provided with slots (1.1.1 & 1.2.1) as shown. The said horizontal slot (1.1.1) is provided for horizontal adjustment of the said positioning bracket when positioned on the seat structure. Said vertical slot (1.2.1) is provided for vertical adjustment of the said pivot block as shown.
A lock bolt (1.3) has been provided to lock the said pivot block (5) against the said vertical surface of said vertical part (1.2). The said locking bolt (1.3) is provided with external threads wherein the said pivot block (5) has been provided with matching internal threads. The extent of locking is dependent on the tightening of the said lock bolt (1.3) against the said vertical face.
The said positioning bracket (1) also has been provided with a marker (1.4) on the said pivot block to help measure the angle subtended by the lower arm (2). The said lower arm consist of an inner (2.1) & outer (2.2) parts telescoping into each other. It has also been provided with a measuring scale (2.3) to indicate the distance between pivots PI & P2 at a given arm position. It has also been provided with locking pin (2.4) and threaded button (2.5) arrangement to hold the length setting. The said threaded button is integral part of the outer part of the lower arm.
The said upper arm consists of an inner (3.1) & outer (3.2) parts telescoping into
each other. It has also been provided with a measuring scale (3.3) to indicate the
distance between pivot P2 & centre of the said sliding probe (4). It has also been
provided with locking pin (3.6) and threaded button (3.7) arrangement to hold the
length setting. The said threaded button is integral part of the outer part of the
upper arm. The said upper arm is also provided with a top block (3.4) which
6

provides as guide for the said sliding probe. The said sliding probe consists of a sector (4.2) & a measuring scale (4.1). During backset measurement, the said sector (4.2) is kept in contact with the front of the head restraint and the measurements are shown on the said measuring scale shown in fig. 8. A spirit level (3.5) is provided above the said top block (3.4) for easy alignment of the apparatus along the vertical longitudinal plane of the seat.
Circular graduated scales (Pl.l & P2.1) are provided at the corresponding pivots to measure the angular positioning of the pivoted parts.
Referring to Fig 05, the locking arrangements at the first pivot PI consist of first locking pin (PI.2), pair of friction washers (PI.3) and threaded button (PI.4). The bottom end of the said inner part of the lower arm has been provided with a slot for accommodating the said pivot block (5) & the said pair washers. The slot is also required for movement of this pivot joint. The said first locking pin (PI.2) is passed through the said circular scale (Pl.l), the inner part of the lower arm, the said washers and the said pivot block and it is engaged with the threaded button. Tightening of the said locking pin induces friction between the intermediate parts which provides the necessary locking at the said pivot PI. It is also possible to attach the said threaded button to the said inner part of the lower arm suitably like by adhesive, welding, brazing etc.
Referring to Fig 06, the locking arrangements at the second pivot P2 consist of second locking pin (P2.2), pair of friction washers (P2.3), intermediate tube (P2.4) and threaded button (P2.5). The top end of the said inner part of the lower arm has been provided with a slot for accommodating the said bottom end of the said upper arm. The bottom end of the said inner part of the upper arm is provided with a slot to permit rotation of the pivot joint. An intermediate tube (P2.4) is also provided inside the slotted section of the bottom end of the said upper arm to avoid collapse of the slotted portion during tightening for locking. The said second locking pin is passed through the said circular scale (P2.1), the outer part

of the lower arm, the said washers, inner part of upper arm and the said intermediate tube and it is engaged with the threaded button. Tightening of the said locking pin induces friction between the intermediate parts which provides the necessary locking at the said pivot P2. It is also possible to attach the said threaded button to the said inner part of the lower arm suitably like by adhesive, welding, brazing etc.
Referring to figure 07, the anti-rotate feature at said first pivot PI comprises pivot block (5) provided with shoulder (5.1) and shank (5.2) such that the width of the shank is just adequate to fit into the said vertical slot (1.2.1). With this arrangement the said pivot block does not rotate about its axis & the orientation of the said lower arm is maintained. In absence of this anti rotate feature orientation of the said lower arm is dependent on the friction between the said pivot block and the said vertical face of the positioning bracket.
During measurement of the head restraint backset, the seat is fixed to a rigid surface. The seat base, seat back & the head restraint are positioned to the design specifications. The backset measurement apparatus is positioned on the seat structure such that the median plane of the apparatus is aligned to the longitudinal vertical plane of the seat and first pivot P1 matches approximately with either H or R point of the seat, depending on the reference of the measurement. The accurate adjustment of the first pivot PI is negotiated through positioning of the positioning bracket through the horizontal slot provided therein and through positioning of the said pivot block vertically through the vertical slot provided therein. The position of the pivot block is set by tightening the locking bolt. The lengths of the lower & upper arms are adjusted to the desired level. The lower arm inclination is then adjusted to the specified torso reference line inclination. The upper arm is aligned to the vertical axis. The sliding probe is moved rearwards till the sector touches the head restraint. The distance between the upper arm vertical axis & the rear end of the sector is shown on the scale provided on the sliding

probe. The radius of the specified headform is subtracted from this reading to get the desired backset.
During this entire process alignment of the plane of symmetry of the apparatus with the vertical median plane of the seat is very critical for the accuracy of the results. For this reason both the upper and lower arms are made up of square tubes, an anti rotate feature is incorporated at the attachment of the pivot block and a spirit level is provided on the top block of the upper arm.
In order to achieve the variety of anthropometries, both the upper and lower arm lengths are adjustable. Both these arms also provided with integrated scales to show their adjusted lengths.
Both the upper & lower arms are pivoted to suit the required angular adjustments. Locking mechanisms are also provided at both these pivots to maintain these angles throughout the measurement. Circular scales are also provided at these pivots to show the angle subtended by the arms.
In order to further speed up the backset measurement process, the measuring scale provided on the sliding probe can be rescaled to show the backset dimension directly by performing the necessary subtraction for the radius of the head.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications and combinations may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

WE CLAIM
1. An improved portable apparatus for measurement of backset of a seat head
restraint comprising
at least one position bracket configured for positioning it on the seat structure;
at least two arms configuring lower arm and upper arm with adjustable lengths and inclinations, pivotally connected to each other of which said lower arm configured to be pivotally connected to said position bracket;
plurality of locking mechanisms for fixing the set lengths and inclinations of said arms;
at least one sliding probe provided through the top block of upper arm to measure the backset of the seat head restraint;
plurality of measuring scales for measuring various lengths and inclinations;
at least one level indicator is provided on the top block of said upper arm to facilitate alignment of said apparatus with vertical axis.
2. The apparatus as claimed in claim 1, wherein said position bracket is 'L' shaped provided with slots on its horizontal and vertical part for horizontal adjustment of said bracket on seat structure and vertical adjustment of pivot block provided for pivotally connecting said lower arm respectively.
3. The apparatus as claimed in claim 1, wherein said lower arm and said upper arm are made up of square shape tube and consist of an inner and outer parts telescoping into each other and inner parts has a measuring scales and outer parts has an integrated locking arrangement for holding the set length of said upper and lower arms.

4. The apparatus as claimed in claim 1 and 2, wherein said pivot block having shoulder and shank configured to fit in the slot provided in vertical part of said bracket and bolted from other side to provide anti-rotate feature about the axis of said pivot block.
5. The apparatus as claimed in claim 1, wherein said measuring scale on said inner part of lower arm is provided for measuring the distance between first pivot and second pivot and measuring scale on said inner part of upper arm is provided for measuring the distance between second pivot and the centre of said sliding probe, and circular graduated scales provided on corresponding pivots to measure the angular positioning of said pivoted parts.
6. The apparatus as claimed in claim 1, wherein said sliding probe comprises a sector at one end to keep in contact with front of the head restraint during backset measurement and a measuring scale to measure the backset.
7. The apparatus as claimed in claim 1, wherein said first and second pivot points having locking arrangement to retain the angular setting of the corresponding linkages forming said pivot joints.
8. The apparatus as claimed in claim 1 and 7, wherein said locking arrangement at first and second pivot comprises locking pins, pair of friction washers and threaded button configured for locking respective arms at required angle and an intermediate tube is provided inside the slotted section of bottom end of said upper arm to avoid collapse of slotted portion due to tightening of locking arrangement.
9. Method of backset measurement by use of apparatus as claimed in preceeding claims, wherein said method comprises the steps of;

• fixing the seat structure to a rigid surface;
• positioning seat base, seat back and head restraint as per design specifications;
• positioning the said backset measurement apparatus on said seat structure such that the median plane of the apparatus is aligned to the longitudinal vertical plane of the seat and first pivot PI matches approximately with either H or R point of the seat, depending on the reference of the measurement;
• adjusting the said first pivot through positioning of the said position bracket through the horizontal slot provided therein and through positioning of the said pivot block vertically through the vertical slot provided therein;
• tightening the locking bolt at the set position of the pivot block;
• adjusting the lengths of said lower and upper arms to the desired level;
• adjusting the inclination of said lower arm to the specified inclination of torso reference line;

• aligning the said upper arm to the vertical axis;
• moving the said sliding probe towards said head restraint till the sector of said sliding prove touches the head restraint;
• noting the distance between vertical axis of said upper arm and the rear end of said sector shown on scale provided on said sliding probe;
• subtracting the radius of the specified headform from the said noted distance to get the desired backset.

10. An improved portable apparatus and method for measurement of backset of a seat head restraint substantially as herein described in the description as illustrated with reference to the accompanying drawings.