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(11) | EP 0 870 975 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Flashlight having low magnetic susceptibility |
| (57) A flashlight constructed of materials including metal components having very low
magnetic susceptibilities is described. The battery powering the flashlight lamp is
a lithium battery also constructed of materials having low magnetic susceptibilities.
The battery further includes a unique terminal configuration that prevents the inadvertent
use of other batteries, including non-magnetic batteries, in the flashlight. |
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention generally relates to a hand held medical device. More particularly, the present invention relates to a flashlight, and still more particularly to a flashlight that is constructed of materials having relatively low magnetic susceptibilities. This provides the flashlight of the present invention as a useful instrument in the vicinity of a magnetic resonance scanner.
2. Prior Art
[0002] The prior art is replete with various types of hand held medical devices such as flashlights made of metal materials that are not useful in the presence of the strong magnetic fields of a magnetic resonance scanner. Examples include U.S. Patent Nos. 1,067,646 to Downey; 1,877,077 to Stevens; 2,459,702 to Hipwell et al.; 2,651,763 to Grimsley; 3,890,498 to Toth, Sr.; 4,203,150 to Shamlian; 4,237,527 to Breedlove; 4,286,311 to Maglica; 5,593,222 to Maglica; and 5,601,359 to Sharrah et al.
[0003] U.S. Patent No. 4,607,623 to Bauman describes a hand held laryngoscope constructed of non-ferrous materials such as ABS with the electrically conductive portions provided by first applying a thin copper layer to the ABS followed by electroless plating and then electrolytically plating another copper layer to form a conductive layer about 0.5 to 2 mils thick. A thin layer of aluminum is subsequentially applied to the copper coating in those areas intended to be reflective. The batteries powering this device are not further described, but may be of a nickel/cadmium type commonly used for such applications. Nickel/cadmium batteries are not considered to be relatively nonmagnetic and would not be useful with the flashlight of the present invention.
[0004] U.S. Patent Nos. 310,004 to Weston; 485,089 to Carhart; 2,282,979 to Murphy; 3,352,715 to Zaromb; 3,673,000 to Ruetschi and 4,318,967 to Ruetschi disclose anti- or non-magnetic materials in cells or batteries. Additionally, U.S. Patent Nos. 2,864,880 to Kaye; 2,982,807 to Dassow et al.; 4,053,687 to Coiboin et al.; 4,264,688 to Catanzarite; 4,595,641 to Giutino; 5,104,752 to Baughman et al.; 5,149,598 to Sunshine; 5,173,371 to Huhndorff et al.; 5,194,340 Kasako; 5,418,087 to Klein; and 5,443,924 to Spellman relate to batteries having means for assuring that proper battery polarity is established. However, none of these patents describe power sources that are useful with the hand held medical device of the present invention because they either include at least some magnetic components, do not have sufficient energy density for extended use or do not have a terminal configuration similar to that of the present invention. U.S. Patent No. 4,613,926 to Heitman et al. discloses an illuminating assembly for an MRI scanner.
[0005] There is needed a flashlight that is predominantly constructed of metal so that the instrument is capable of withstanding the abusive treatment conditions which surgical instruments are sometimes subjected to. For this purpose, the flashlight of the present invention is constructed largely of metal components. However, with ever increasing use of magnetic resonance scanning to aid medical personnel during pre- and post-clinical and surgical procedures, the metal components must be constructed of materials that have as low a magnetic susceptibility as possible.
SUMMARY OF THE INVENTION
[0006] The flashlights of the present invention is constructed of materials including metal components having very low magnetic susceptibilities. Those parts not made of metal are preferably formed of a thermoplastic material, for example an acetal compound such as DELRIN. The battery powering the flashlight lamp is also constructed of materials having low magnetic susceptibility. Lithium batteries are preferred, and all components such as the casing, terminal leads, current collectors and collector leads, some of which are typically made of nickel, are constructed of stainless steel nonmagnetic austenitic. The battery further includes a unique terminal configuration that prevents the inadvertent use of other batteries, including non-magnetic batteries, in the laryngoscope.
[0007] These and other aspects of the present invention will become more apparent to those skilled in the art by reference to the following description and to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Fig. 4A is a partial, cross-sectional view of a portion of the handle 12 and the head 14 for the flashlight 10.
[0012] Fig. 4B is a partial, cross-sectional view of the handle 12 and end cap 50 for the flashlight 10.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Turning now to the drawings, Figs. 1 to 6 show a flashlight 10 having low magnetic susceptibility characteristics according to the present invention generally comprised of a handle 12 and a head 14 supporting a lamp actuation means 16 mounted on the head 14 in a twistable relationship therewith to activate and deactivate the flashlight as desired. The instrument is utilized to illuminate an object of interest, for example in a health care environment and particularly in close proximity of the strong magnetic fields of a magnetic resonance unit (not shown).
[0016] With particular reference to Figs. 3B, 4A and 4B, the handle 12 is a cylindrically-shaped tube comprising an intermediate section 18 meeting at a step 20 with a proximal section 22 having internal threads 24, and the intermediate section 18 meeting at a chamfer 26 with a distal section 28. The outer surface of the handle 12 is provided with raised, knurled ridges 30 (Fig. 1) to aid in gripping the flashlight 10. The handle 12 is preferably constructed of chrome plated brass.
[0017] A battery 32 (Figs. 3B, 4A, 4B, 5 and 6) is housed inside the intermediate handle Section 18 for providing power to a lamp means as an assembly 34, which will be described in detail hereinafter. The battery 32 is constructed of materials having relatively low magnetic susceptibility with a unique terminal configuration according to the present invention. The battery 32 is preferably an alkali metal battery and more preferably an alkali metal/liquid catholyte battery. A most preferred chemistry utilizes the lithium/thionyl chloride-bromine chloride (Li/BCX) couple. The battery casing adjacent to the distal handle section 28 is insulated to prevent electrical contact in the conventional manner.
[0018] As shown in Figs. 4A, 5 and 6, the opposite end of the battery 32 includes a negative contact ring 36 that is permanently attached to the battery case to provide one terminal for the battery. The central, positive terminal 38 is recessed and insulated 40 around its perimeter to prevent accidental shortening. A non-magnetic fuse 42 prevents inadvertent run-away electrochemical reaction while a thermoplastic insulator plate 44 supported on a ledge of the insulated material 40 protects the positive terminal 38 and fuse 42. A central opening 46 in plate 44 provides for access to the positive terminal 38. To provide the battery 32 having a relatively low magnetic susceptibility, all external and internal electrical components such as the casing, the terminals 36, 38, the current collectors and the contact leads are of stainless steel.
[0019] The unique terminal configuration prevents the inadvertent loading and discharge of batteries into the handle 12 not intended for use with the flashlight 10. Such inadvertent battery use could have detrimental affects on the flashlight's low magnetic susceptibility characteristics.
[0020] The battery 32 is secured inside the handle 12 by a cap spring 48, preferably of silver plated beryllium copper, that biases between the battery and an end cap 50 snug-fitted into the distal handle section 28 extending part way into the intermediate handle section 18. The end cap 50 is of a non-magnetic material, such as an acetal thermoplastic material with an enlarged head 52 that abuts the distal end of handle 12. A groove 54 formed between the cap head 52 and an annular protrusion 56 of the cap receives an O-ring 58 of a flexible elastomeric material for sealing the cap 50 in the distal section 28 of the handle 12.
[0021] As shown in Figs. 3B and 4A, a battery retainer assembly is threaded into the proximal handle section 22 and includes a battery retainer 60, preferably of an acetal thermoplastic material, that threads into the handle 12 to capture a battery pin 62, a battery spring 64, a tube disk 66 and a pair of spring contacts 68 therein. The battery pin 62 is preferably of gold plated brass, the battery spring 64 is preferably of silver plated beryllium copper, the tube disk 66 is of an acetal thermoplastic material and the spring contacts 68 are of silver plated beryllium copper.
[0022] The battery retainer 60 comprises a threaded portion 70 sized to threadingly mate with the internal threads 24 of the proximal handle section 22. The threaded portion 70 of the battery retainer 60 meets a cylindrically-shaped portion 72 that extends to a chamfer 74 ending at an end face 76. The battery retainer 60 has a first, cylindrically-shaped bore 78 that meets at an internal shoulder 80 with a second, lesser diameter cylindrically-shaped bore 82 extending to the end face 76. A pair of diametrically opposed openings 84 are provided through the thickness of the threaded portion 70. The battery retainer 60 receives the battery pin 62 having a cylindrically-shaped body 86 provided with an annular protrusion 88 adjacent to a proximal end 90 thereof.
[0023] The internal threads 24 at the proximal handle section 22 terminate at an internal shoulder 92. Shoulder 92 supports the tube disk 66 having a central opening 94. The tube disk 66 also includes a pair of opposed channels 96 (shown in dashed lines in Fig. 3B) that communicate between the outer edge thereof and diametrically opposed portions of the opening 94. The tube disk 66 supports the pair of spring contacts 68, each having a leg disposed in one of the disk channels 96 with a contact portion 98 of the springs extending from the opposite face of the tube disk 66.
[0024] As shown in Fig. 4A, with the tube disk 66 supported on the internal shoulder 92, the spring contacts 68 are captured between the shoulder 92 and the disk 66 with the contact portions 98 contacting the annular, negative terminal 36 of battery 32. The tube disk 66 and spring contacts 68 are secured in this position by the battery retainer 60 threaded into the proximal handle section 22. The battery retainer 60 further captures the battery pin 62 between itself and the tube disk 66 with the proximal end side of the annular protrusion 88 abutted against the internal shoulder 80 of the battery retainer by the battery spring 64 surrounding the body 86 of the battery pin 62 and biasing between the tube disk 66 and the opposite side of the annular protrusion 88. The pair of diametrically opposed openings 84 in the battery retainer 60 are provided to receive a tool (not shown) such as a spanner wrench for tightening the battery retainer 60, battery pin 62, battery spring 64, tube disk 66 and spring contacts 68 into position. The battery retainer assembly together with the battery 32 loaded into the handle 12 and secured therein by the cap spring 48 and end cap 50 form the portion of the flashlight 10 of the present invention generally referred to as the battery pack assembly.
[0025] After the battery retainer assembly is threaded into the proximal handle section 22, the proximal section 22 threadingly receives the head 14. The head 14 is of copper plated brass. As shown in Figs. 1, 2, 3A and 4A, the head 14 for the flashlight 10 of the present invention comprises a base portion 100 having exterior threads 102 that mate with the interior threads 24 of the proximal handle section 22 for attaching the head 14 to the handle 12. An external, inwardly curved section 104 is between the base portion 100 and a mounting portion 106 having an annular channel 108 which receives an elastomeric O-ring 110.
[0026] The mounting portion 110 of head 14 is provided with three partially overlapping races 112. The races 112 each begin at a position adjacent to a proximal open end 114 of the mounting portion 110 and they run towards the base portion 100 of the head 14 as they extend somewhat more than a third of the way around the circumference thereof. Thus, a beginning portion of a first race adjacent to the proximal open end 114 overlaps the end of a second race 112 adjacent to the curved section 104 of head 14 while the end of the first race is overlapped by the beginning a third race. The races 112 provide for twistingly mounting a cage 116 and sleeve 118 on the mounting portion 110 of head 14 such that as the cage 116 and sleeve 118 are twisted, they move axially along the flashlight 10, as will be described in detail hereinafter.
[0027] The interior of the mounting portion 110 of head 14 is provided with a first, cylindrically-shaped surface 120 that meets a second cylindrically-shaped surface 122 at an inner step 124. The second cylindrical surface 122 forms into a bevel 126 meeting a shoulder 128 leading to a third, cylindrically-shaped surface 130 in the curved section 104 of the head. Third cylindrical surface 130 leads to an outwardly tapering bevel 132 that meets a fourth, cylindrically-shaped surface 134 and a second bevel 136 in the base portion 100 of head 14.
[0028] A spacer 138, preferably of an acetal thermoplastic material, has a cylindrical outer surface 140 extending into a distal chamfer 142. The cylindrical outer surface 140 and chamfer 142 of spacer 138 are received in a closely spaced relationship by the matching second internal cylindrical surface 122 and bevel 126 of the head member 14 with the chamfer 142 abutting the bevel 126.
[0029] The inner step 124 of the head 14 between the first cylindrical surface 120 and the second lesser diameter cylindrical surface 122 supports a contact spring 144 thereon. The contact spring 144 is preferably of beryllium copper plated with silver.
[0030] A lamp holder 146 has a cylindrically-shaped outer surface 148 that is received in a closely spaced relationship with the third, internal cylindrical surface 130 of head member 14, directly opposite the inwardly curved section 104. The lamp holder 146 is preferably of gold plated brass and has a first, inner cylindrical section 150 that meets at an inner step 152 with a second, inner cylindrical section 154 which in turn meets at a step 156 with an inner threaded section 158. Threaded section 158 opens into a fourth, inner cylindrical section 160 that meets an outwardly tapering bevel 162 extending to a proximal end thereof.
[0031] A forward insulator 164, preferably of an acetal thermoplastic material, is received inside the lamp holder 146 with its end 166 abutting step 156 and its cylindrically-shaped outer surface 168 contacting the second cylindrical section 154. Forward insulator 164 has a cylindrically-shaped through bore 170 of a first diameter that opens into an annular inlet portion 172 having a second diameter greater than that of bore 170.
[0032] A contact pin 174 comprises a large diameter disk 176 intermediate a forward shaft 178 and a rearward shaft 180 extending to a contact 182. The contact pin 174 is preferably of gold plated brass and the forward shaft 178 is sized to be received in the through bore 170 of the forward insulator 164. With the forward insulator 164 received in the lamp holder 146, the disk 176 of contact pin 174 is positioned within the second, inner cylindrical section 154 of the lamp holder 146 adjacent to step 152. A rear insulator 184, preferably of an acetal thermoplastic material, has a cylindrically-shaped outer surface 186 meeting opposed end faces 188 and 190. A cylindrical through bore 192 communicates between the faces 188, 190 and is sized to fit over the rearward shaft 180 of the contact pin 174 to thereby lock the pin 174 inside the lamp holder 146 in conjunction with the forward insulator 164.
[0033] A lamp 194 is threaded into the inner threaded section 158 of the lamp holder 146. A lamp 194 useful with the flashlight 10 of the present invention is commercially available from Boehm under model no. X02.88.044. A reflector 196, preferably of silver plated beryllium copper, has a step 197 that serves as a seat for an end of the contact spring 144. When the reflector 196 is fitted into the fourth, inner cylindrical section 160 of the lamp holder 146 to surround the lamp 194 in a reflective relationship therewith, the contact spring 144 is captured in a biasing relationship between the reflector 196 and the inner step 124 of head 14. The reflector 196 is preferably of gold plated brass. A stainless steel contact spring 198 is received in an annular channel 200 in the base 202 of the reflector 196, and spring 198 helps to retain the reflector 196 in position in addition to serving as an electrical contact between the reflector 196 and the lamp holder 146.
[0034] A sleeve 204, preferably of gold plated brass, comprises an inner, cylindrical portion 206 having a first diameter meeting a second, larger diameter inner, cylindrical portion 208 at a step 210. A portion of the outer surface of sleeve 204 adjacent to the end of the second cylindrical portion 208 is threaded 212.
[0035] A cage 214, preferably of an acetal thermoplastic material, has a cylindrical outer surface with three openings 218 spaced equidistant around the perimeter of the cage 214. The openings 218 form a plane normal to the longitudinal axis of the flashlight 10 and receive stainless steel balls 220. With the cage 214 positioned inside the sleeve 204 resting on step 210 and with the cage 214 and sleeve 204 mounted over and around the mounting portion 106 of the head 14, one ball 220 is captured in each opening 218 and one of the races 112 of the mounting portion 106 and the assembly is held in that position by sleeve 204. The sleeve 204 is in turn secured in position by a lens 222 and an associated lens ring 224 which threads onto the mounting portion 106 of head 14. The lens and ring are preferably of an acetal thermoplastic material.
[0036] Fig. 4A shows that with the head 14 threadingly connected to the proximal handle section 22 and with the sleeve 204 and cage 214 positioned so that each ball 220 is at the beginning of its race 112 adjacent to the proximal open end 114 of the mounting portion 106 of head 14, the contact 195 of lamp 194 contacts the forward shaft 178 of the contact pin 174 having its rearward shaft 180 contacting the proximal end 90 of the battery pin 62. However, the opposite, distal end 226 (Figs. 3B and 4A) of the battery pin 62 is in a raised position, out of contact with the central, positive terminal 38 of battery 32. The lamp 194 is energized by twisting or rotating the sleeve 204 with respect to the head 14 and handle 12. This movement causes the sleeve 204 and the captured cage 214 to move towards the handle 12 as the balls 220 travel along the races 112 towards their ends thereof. This movement causes the lamp holder 146, lamp 194, reflector 196, lens 222 and lens ring 224 to move towards the handle 12 against the biasing force of the contact spring 144 which in turn pushes the contact pin 174 and battery pin 62 towards the battery 32 against the biasing force of the battery spring 64 until the distal end 226 of the battery pin 62 contacts the central, positive terminal 38 of battery (as shown in dashed lines in Fig. 4A). The electrical circuit is completed through the annular, negative contact ring 36, the spring contacts 68, the handle 12, the head 14, the lamp holder 146, the reflector spring 198 and reflector 196 contacting the casing of lamp 194. With the lamp 194 energized, light is directed out through the lens 222, for example to help illuminate a zone of interest during a medical examination or procedure.
[0037] When the sleeve 204 is twisted in the opposite direction, the sleeve 204 and cage 214 move away from the handle 12 as the balls 220 travel along the races 112 towards their beginnings adjacent to the proximal open end 114 of the mounting portion 110 of head 14. As this occurs, the contact spring 144 biases the lamp holder 146, lamp 194, reflector 196, lens 222 and lens ring 224 away from the handle 12 while the battery spring 64 biases the battery pin 62 out of contact with the central, positive battery terminal 38.
[0038] In accordance with the stated low magnetic susceptibility characteristics of the flashlight of the present invention, Table 1 lists the magnetic susceptibilities of the various materials used to construct the flashlight along with selected other materials.
TABLE 1
| Material | Density (g/cc) | Atomic or Molecular Weight | Susceptibility (x 106) |
| Carbon (polycrystalline graphite) | 2.26 | 12.011 | -218 |
| Gold | 19.32 | 196.97 | -34 |
| Beryllium | 1.85 | 9.012 | -24 |
| Silver | 10.50 | 107.87 | -24 |
| Carbon (diamond) | 3.513 | 12.011 | -21.8 |
| Zinc | 7.13 | 65.39 | -15.7 |
| Copper | 8.92 | 63.546 | -9.63 |
| Water (37°C) | 1.00 | 18.015 | -9.03 |
| Human Soft Tissues | ∼1.00-1.05 | - | ∼(-11.0 to - 7.0) |
| Air (NTP) | 0.00129 | 28.97 | +0.36 |
| Stainless Steel (nonmagnetic, austenitic) | 8.0 | - | 3520-6700 |
| Chrome | 7.19 | 51.996 | 320 |
[0040] In contrast, Table 2 lists the magnetic susceptibilities of various relatively highly magnetic materials.
TABLE 2
| Material | Density (g/cc) | Atomic or Molecular Weight | Susceptibility |
| Nickel | 8.9 | 58.69 | 600 |
| Stainless Steel (magnetic, martensitic) | 7.8 | - | 400-1100 |
| Iron | 7.874 | 55.847 | 200,000 |
[0041] The data use to construct Tables 1 and 2 was obtained from a paper authored by John Schneck of General Electric Corporate Research and Development Center, Schenectady, New York 12309, entitled "The Role of Magnetic Susceptibility In Magnetic Resonance Imaging:Magnetic Field Compatibility of the First and Second Kinds". The disclosure of that paper is incorporated herein by reference.
1. A flashlight, which comprises:
(a) a handle means;
(b) a lamp means;
(c) a sleeve means surrounding at least a portion of the handle means, wherein the sleeve means is in a rotatable relationship with respect to the handle means; and
(d) a battery housed inside the handle means to electrically energize the lamp means, wherein the battery has a first end facing the lamp means and a second end, and wherein the second end and at least part of the battery side wall between the ends are provided with an insulative material to prevent electrical contact therewith, and wherein the first end of the battery comprises a first, continuous terminal surrounding a second terminal such that with the sleeve means in a first, unrotated position, spaced a maximum distance from the battery, the lamp means is in an unenergized state and wherein when the sleeve means is rotated with respect to the handle means, the lamp means is caused to move inside the handle means to make electrical contact with the second terminal to thereby complete an electrical path that energizes the lamp means.
2. The flashlight of claim 1, wherein the first, continuous terminal of the battery is
in the shape of a ring at the first end of the battery.
3. The flashlight of claim 1 or claim 2, wherein the second terminal of the battery is
centered along a longitudinal axis of the battery.
4. The flashlight of any of claims 1 to 3, wherein the first, continuous terminal of
the battery comprises a ring at the first end, and the second terminal is disposed
in a recessed position towards the second end of the battery with respect to a plane
of the ring.
5. The flashlight of any of claims 1 to 4, wherein a cage means is disposed between the
sleeve means and the handle means and wherein the cage means surrounds a portion of
the handle means provided with a plurality of partially overlapping races that each
extend from a beginning position adjacent to a distal end of the sleeve means, spaced
a maximum distance from the battery and travel a portion of the distance about the
circumference of the handle means to an end position spaced closer to the battery,
wherein a ball is captured in each of the races by the sleeve means and the cage means
to provide the rotatable relationship between the sleeve means and the handle means.
6. The flaslight of claim 5, wherein the sleeve means is rotated with respect to the
handle means to cause the balls to travel along the races from the beginning position
of the races to the end position thereof to thereby energize the lamp.
7. The flashlight of claim 6, wherein there are three races extending about the circumference
of the handle means.
8. A flashlight, which comprises
(a) a handle means;
(b) a lamp means;
(c) a sleeve means surrounding at least a portion of the handle means, wherein the sleeve means is in a rotatable relationship with respect to the handle means to cause the lamp means to move axially along the longitudinal axis of the handle means; and
(d) a battery housed inside the handle means to electrically energize the lamp means, wherein with the sleeve means in a first, unrotated position spaced a maximum distance from the battery, the lamp means is in an unenergized state and wherein when the sleeve is rotated with respect to the handle means, the lamp is caused to move inside the handle means to complete an electrical path with the battery to energize the lamp means, and wherein the battery is an alkali metal battery housed inside of an austenitic stainless steel casing having a magnetic susceptibility of about 6,700 x 106 or less and wherein the internal electrical battery components, the handle means, the sleeve means and the lamp means have magnetic susceptibilities at least as low as that of austenitic stainless steel.
9. The flashlight of claim 8, wherein either of or both of said handle means and said
sleeve means are of chrome plated brass.
10. The flashlight of any of claims 1 to 9, wherein the battery comprises:
(a) a casing;
(b) an anode housed inside the casing;
(c) a cathode housed inside the casing in operative association with the anode;
(d) a first terminal connected to one of the anode and the cathode;
(e) a second terminal connected to the other of the anode and the cathode, wherein the casing has a side wall between opposed first and second ends and wherein the second end and at least part of the casing side wall are provided with an insulative material to prevent electrical contact therewith, and wherein the first end of the battery comprises the first terminal as a continuous member surrounding the second terminal.
11. The flashlight of claim 10, wherein the first, continuous terminal of the battery
comprises a ring at the first end, and the second terminal is disposed in a recessed
position towards the second end of the battery with respect to a plane of the ring.
12. The flashlight of any of claims 1 to 11, wherein the battery is an alkali metal battery
or a lithium/thionyl chloride - bromine chloride battery.
13. A method of assembling a flashlight, comprising the steps of
(a) providing a handle means;
(b) mounting a sleeve means surrounding at least a portion of the handle means, wherein the sleeve means is in a rotatable relationship with respect to the handle means;
(c) housing a lamp means inside the handle as a light source;
(d) providing a battery inside the handle means to electrically energize the lamp means, wherein the battery has a first end facing the lamp means and a second end, and wherein the second end and at least part of the battery side wall between the ends are provided with an insulative material to prevent electrical contact therewith, and wherein the first end of the battery comprises a first, continuous terminal surrounding a second terminal; and
(e) rotating the sleeve means between an unrotated position, spaced a maximum distance from the battery with the lamp means in an unenergized state, and a rotated position causing the lamp means to move inside the handle means to make electrical contact with the second terminal to thereby complete an electrical path that energizes the lamp means.
14. The method of claim 13, including providing the first, continuous terminal of the
battery in the shape of a ring at the first end of the battery.
15. The method of claim 13 or claim 14, including providing the second terminal of the
battery centered along a longitudinal axis of the battery.
16. The method of any of claims 13 to 15, including providing the first, continuous terminal
of the battery comprising a ring at the first end, and the second terminal disposed
in a recessed position towards the second end of the battery with respect to a plane
of the ring.
17. The method of any of claims 13 to 16, including providing the battery as an alkali
metal battery.
18. A method of assembling a flashlight, comprising the steps of
(a) providing a handle means;
(b) mounting a sleeve means surrounding at least a portion of the handle means, wherein the sleeve means is in a rotatable relationship with respect to the handle means;
(c) housing a lamp means inside the handle as a light source;
(d) providing a battery housed inside the handle to electrically energize the lamp means, including providing the battery as an alkali metal battery housed inside of an austenitic stainless steel casing having a magnetic susceptibility of about 6,700 x 106 or less, and further providing the internal electrical battery components, the handle means, the sleeve means and the lamp means having magnetic susceptibilities at least as low as that of austenitic stainless steel; and
(e) rotating the sleeve means between an unrotated position, spaced a maximum distance from the battery with the lamp means in an unenergized state, and a rotated position causing the lamp means to move inside the handle means to contact the battery energizing the lamp means.
19. The method of claim 18, including providing either of or both of said handle means
and said sleeve means of chrome plated brass.