CA1120296A - Microfiche reader - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A microfiche reader according to the present invention includes a housing consisting of a hood portion and a base por-tion, a screen located within the hood portion and visible through the front end of the hood, a combined microfiche carriage and index holder, a lens assembly and a projection system. The com-bined microfiche carriage and index holder serves to accurately locate the microfiche with respect to the index grid. By reason of the fact that there is no relative movement between the index grid and the microfiche in use, it is always possible to accurately locate the microfiche with respect to the projection system by reference to the index grid. The index grid is illuminated by an index illuminating lens carried by the housing. The illuminating lens is located in a fixed relationship with respect to the pro-jection path which again contributes to the facility with which the microfiche may be accurately located in the projection path.
The lens assembly includes a support plate mounted above the microfiche carriage and a slide member mounted in the support plate and a pair of lens members mounted in the slide members so that either one may be located in the projection path as re-quired. The projection system includes a demountable modular unit which may be easily mounted in and removed from the housing.
A prefocussed lamp is mounted on the modular unit and the position of the prefocussed lamp with respect to the modular unit may be adjusted so as to vary the length of the illuminating path between the prefocussed lamp and the condenser means whereby the optical system may be adjusted to accommodate objective lenses having different characteristics. The projection system consists of a prefocussed lamp which projects a beam of light onto a cold mirror which reflects the beam of light through an optical con-denser which in turn directs the beam of light through the micro-fiche to an objective lens mounted thereabove. A first surface mirror is mounted in the housing and reflects the bean of light emitted from the objective lens to a viewing screen mounted in the housing. The viewing screen consists of a unitary body of molded plastics material having an image receiving surface formed with a concave spherical curvature.
The image receiving surface may be plated with a suitable coating to form an image reflecting coating thereon.

Description

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This invention relates to improvements in a micro-fiche reader. In particular, this invention relates to improve-ments in a front projection type of microfiche reader.
PRIOR ART
In the microfiche readers which are presently avail-able, a microfiche is located in a movable holder for movement with respect to the illuminating path of the projection system and a corresponding grid pattern is located in a stationary position with respect to the microfiche housing. The microfiche holder has an indexing finger projecting outwardly therefrom to overlie the indexing grid. The indexing finger may be located at any position with respect to the indexing grid to locate the corresponding portion of the microfiche in the projection path. secause the microfiche holder and, therefore, the micro-fiche is movable relative to the indexing grid, the microfiche may be slightly misaligned with respect to the grid making the location OI a specific area of the microfiche difficult at times. In addition, the clearances between the relatively moving components of the microfiche holder and indexing grid are such that difficulties can be experienced in obtaining correct alignment of the microfiche.
I have overcome the above difficulties by reason of the fact that the indexing grid and microfiche are mounted in a unitary microfiche carriage and index holder so that no relative movement occurs between the indexing grid and the microfiche when the apparatus is in use.
Considerable difficulty has also been experienced in attempting to provide an undercarriage support system for the microfiche carriage which will adequately support the carriage for movement witll respect to the projection path of the reader.

This difficulty has been overcome by provicling an undercarriage which has V-shaped support rails and V-shaped wheels cooperating with one another and rails on the support platform of the micro-fiche reader to provide a minimum backlash in the system in response to movement of the microfiche carriage~
In a microfiche reader, it is important to ensure that the microfiche may be located in and removed from the microfiche carriage as easily as possible. I have achieved this desirable result by providing an upper glass flat which is automatically raised as the microfiche carriage is moved to a predetermined position forwardly of the platform of the reader to provide access to the microfiche for removal.
The servicing of the projection system of a microfiche reader is generally limited to a requirement that the illumina-ting light may be readily replaced. This is achieved in accord-ance with one aspect of the present invention by reason of the fact that the lamp is mounted in a modular unit which may be removed from the reader housing.
In many instances, it is desirable to be able to change the objective lens of a microfiche reader so that the reader may be used for a variety of purposes. When the objective lens is changed in the known readers, considerable adjustment of the optical system is required. This difficulty is overcome by one aspect of the microfiche reader of the present invention which provides a prefocussed lamp which is mounted to be adjustably movable towards and away from the condenser lens of the projection system whereby the projection system may be adjusted to accom-modate objective lenses having different charac-teristics by the movement of the position of the prefocussed lamp with respect to the condenser lens. Preferably, the prefocussed lamp is mounted to be adjustably movable with respect to the modular unit which is removable from the main housing of the reader.
To adjust the magnification of the projected image in known microfiche readers, the objective lens is removed and replaced by another lens. This adjustment requires a knowledge of the structure of the microfiche reader assembly and can create difficulties for operators not familiar with the structure. This ; difficulty has been overcome according to one aspect of the microfiche reader described herein by mounting a pair of object-ive lenses in a slide member which is slidably mounted in a sup-port plate above the microfiche carriage, the lenses being re-leasably secured in the illuminating path of the projector as required in use.
The majority of microfiche readers presently in use have a projection system which requires a power-driven fan in order to provide adequate cooling. Because of the very sub-stantial amount of heat generated by the conventional optical system, it has been necessary to make the housings relatively large and to provide a powerful fan~driven cooling system. The fan-driven cooling system is noisy and creates a further source of service difficulties. These difficulties are overcome by one aspect of the apparatus described herein which provides an optical system and venting system and housing construction which permits the microfiche reader to operate without the use of a forced-air cooling system.
Considerably difficulty has also been experienced in providing a screen for a microfiche reader which has adequate reflective characteristics to function effectively as a screen in a front projection system. The screen of the microfiche reader according to one aspect of the present invention overcomes this difficulty and ls Eormed from a unitary body of molded plastics material which has an image receiving surface formed with a concave spherical curvature and which is coated with a layer of an image reflecting materia:L.
SUMMARY OF IN~7ENTION
According to one aspect of the present invention, there is provided in a microfiche reader of the type having a housing, an image projection system :including projector means and a screen for receiving a projected image and an illuminating path extending from the projector means to the screen, the improve- :ment of a combination mircofiche carriage and index holder which comprises a frame, a first window opening through said frame, means for locating a microfiche in a predetermined position with respect to said first window for the projection of light there-through, a second window opening through said frame, a trans-parent index grid mounted in said second window in a predeter-mined position with respect to said second window for the projec-tion of light therethrough, index illuminating means underlying said second window and located in a fixed relationship with res- :
pect to a portion of the illuminating path which projects through said first window opening, said frame being mounted for planar ~:
movement with respect to said housing to locate any required area of the grid in the beam of light emanating from the index illumin~
ating means and thereby to locate the corresponding areas of the microfiche in the illuminating path of the projector for pro-jection onto the screen.
According to a further aspect of the present invention, there is provided in a microfiche reader of the type having a .~
housing, an image projection system including projector means and -a screen for receiving a projected image and an illuminating path .

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extending from the projector means to the screen, a microfiche carriage having an upper glass flat arranged to be disposed above a microfiche in the carriage, the improvement of a lens assembly which comprises a support plate mounted above said microfiche carriage, passage means opening through said support plate in alignment with the illuminating path of said projector, a slide member mounted in said support plate for movement relative there-to, a pair of lens passages opening through said slide member, a lens holder mounted in each of said lens passages, a lens member releasably mounted in each of said lens holders, said carriage means being slidable relative to said support plate to locate one or other of said lens members in said illuminating path of said projector, and releasable lock means for releasably locking either of said lens members in said illuminating path in use.
According to a further aspect of the present invention, there is provided a microfiche reader of the type having a hous-ing, a viewing screen located within said housing and a projection system for projecting an illuminating beam of light along an illuminating path, said illuminating beam being directed through a condenser lens, a microficha and an Qbjective lens arranged in series and onto said screen, the improvement wherein said pro-jection system includes a demountable modular unit which comprises a frame removably mounted in an operative position in said hous-ing, mirror means mounted in said frame in a fixed position with respect to said frame, said mirror means being located in said illuminating path when said frame is in said operative position, a prefocussed lamp mounted in said frame for movement towards and away from said mirror means to vary the length of the illumin-ating path between the prefocussed lamp and the condenser means whereby the optical system may be adjusted to accommodate object-ive lenses having different characteristics.

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~2~6 According to a further aspect of the present invention, there is provided a microfiche reader of the front projection type having a housing, a microfiche carrier mounted in said housing and a projection system for projecting an illuminated image from a microfiche, the improvement wherein saia projection system com-prises a prefocussed lamp mounted i:n said housing providing a : source of a beam of light, a cold mirror mounted in said housing in the path of the beam of light emitted from said prefocussed lamp for reflecting said beam, an optical condenser mounted in said housing in the path of the beam of light reflected by said cold mirror, said ~tical condenser directing the beam of ~ht through the microfiche carrier, an objective lens mounted in said housing for receiving the beam of light transmitted through said microfiche carrier, a first surface mirror mounted in said housing in the path of the beam of light emitted from said ob-jective lens, a viewing screen mounted in sald housing for re~
ceiving the illuminated ~eam of light reflected from said first sur~ace mirror, said prefocussed lamp being adjustable towards and away from said optical condenser whereby the projection system may be adjusted to accommodate objective lenses having different characteristics.
According to a further aspect of the present invention, there is provided a microfiche viewer having a housing, a screen mounted in said housing and a front projection system for pro-jecting images from a microfiche onto a screen, the improvement wherein said screen comprises a unitary body of molded plastics material having an image receiving surface formed with a concave spherical curvature, said image receiving surface being coated with a layer of image reflecting material.

Accordlrlg to a further a.æpect Or the pre~ent invention, there is provided a microfiche viewer having a housin6 "~herein the ~creen ha~ an upper edge and a lower edge, and a pair Or side edges, said side edges converging wlth respect to one another whereby the screen has an :~mage receiving surface which is narrower at said upper edge than it is at said lower edge to conform to the con~iguration of the pro~ected i~age.
-The invention will be more clearly understood after reference to the following detailed specification read in con-~unction with the drawings wherein, Fig. 1 is a pictorial front view of a micro~lche reader according to an embodiment of the present invention ;
Fig. 2 is a top view of the plat~orm o~ the micro~iche reader and an exploded view of the microfiche carriage of Fig. l;
Fig. 2a is an exploded top view of the platform Or the microfiche reader ;
Fig. 3 is an e~ploded view of the hood portion of the micro~iche reader of Fig. 1 ;
Fig. 4 ls a sectioned p~ctor~al view Or the lens support plate ;
Fig. 5 ~s a pictorial view of the lens holder assembly;
Fig. 6 is a pictorial back view of the screen ;
Fig. 7 is a diagrammatic illustratlon of the projection system and inde~ing system of the microfiche reader ' Fig. 8 is a pictorial side view of the microfiche carriage located on the support plat~orm of the micro~iche reader ;
Fig. 9 'Ls a sectional vLew through a support rail and the undercarriage lllu~trating the rail and wheel configuration.
A microriche reader according ko an embodiment of the present invention is lllustrated in Fig. 1 of the drawings, In ~æ~æ~

. 1 of the dra~:.ir.r~s tne refe~e~ce -.u-r-ra~ 1~ refe s ~-ene~a o tne microf che reader housing ~.hich cc.~s~sts of z nooc nort on 12 a~d ~ base ~orvion 14. ~ scree~ is lcc2 ec~ Tithin the ;~ood 12 anc ic vi~iDl throu~h the frs-.v e~.~ a~ ~e hooc. ~ co~.-~ined ~icrori che carria.rr ana incex h^lser 1~ s sl-~rorte~ on thr ~ase rortion 14 and is moun.ted for move~P~ respe^t to thr base portion. A lens assembly 20 is ~ounted in the hood 12 and aisposed above he carriage 18.
ICROFIC~ C.A~RI.~5E

-14 The structure of the combined microfiche carriage and index holàer 18 and its support s ructure is illustrated in Figs.

2, 8 and 9 of the dra-.~ings. The combined microfiche carriage and index holder 18 cbnsists of a frame 22 ~hich has a first window 24 opening therethrough and a second windo~ 26 opening therethrough. The lower glass flat 28 (Fig. 8) is located in the first ~indow 24 and an upper ~lass flat holder 30 is pivot-ally mounted by means of lugs 32 in recesses 34. The lugs 32 form hin~es about which the upper glass flat 30 may pivot so as to be raised out of engagement with the lo~er glass fl2t 28.
An actuator extension 36 extends rear~ardly and upwardly from the back edge of the upper glass flat holder. The actuator extension 36 engages the lug 38 located on the underside of the lens support plate 40 (Fig. 3) so that when the carriage 18 is moved outwardly to-~ards the operator, the actuator extension will at a prede-termined location cause the upper glass flat to pivot u~wardly to facilitate the location of a microfiche 44 ~etween the lo~Jer glass flat 28 and the upper glass ~lat 30. An index grid 4~
is located in the second windo~7 26. Two sets of ribs 48 extend across the underside of the carriage 18 in a sraced parallel relationship.

As sho~J~ in Fl r. 9 0~ the cra~".~Fs, e '~ h~?~n w~eel 50 is mounted for rotat~on on a sha~t 52 which is supported ~J
the ribs 4~. h plurali~y Or ~Jheels 50 a~e located ir. thLs manner in a chan~lel 5ll lormed be~-v~een the ri~s ~8 2v s~aceQ i~erv21 s -alollF the length of the ribs- ~ rectznc,~llzr sh2pec undercarriag_ 56 is formea ~:ith a pair of supporv rails 52~ extendin~, trar.s-versely thereof and a pair of ~-sna~ed cr.annel members 6Q e,-.ter.c'-ing longitudinally tnereof. As sho-;~!n in ~ir. 9 ~ the drawings, each of the rail members 58 has a 'V-shape~ rail portion 62 which is proportioned to support the V-shaped ~neels 50. A pluralitv of additional wheel members 50 are located in the 11-sha~ed channel members 60 at spaced intervals zlong the len~th thereof.
Channels 64 are rormed in the surface of the platform 66 of the base member 14. Support rails 68 of the same contour as the rails 62 extend longitudinally of the channels 64. A narrow lip portion 70 projects outwardl~ from an outer side edge of each channel 64. In use, the lip 70 overlies the ledge,72 which pro-jects outwardly from the side of the U-shaped channel members 60 and serves to retain the undercarria~e 56 in engagement with the rail'member 58.
To mount the und~rcarriage 56 on the platform 64~ it is located towards the front end of the platform and lowered to a posltion in which the wheel members 50 carried by the under-carriage rest on the support rails 64. The carriage 22 is mounted on the undercarriage 56 by locating the wheel members 50 on the guide rails 62. Longitudinal movement of the carriage 18 with respect to the reader is achieved by the movement o~ the undercarriage 56 along the support rails 68 and transverse move-ment is achieved py transverse movement o~ the carriage 26 witn respect to the undercarriage 58 by the movement Or the support wheels 50 along the guide rails 62.

~s sho-;~n in ~i~s. 2 ar.c 2a Or t:~e dra:!~ n~s ~ z~. inde7:
illuminating passage 74 oper.s ~nrough the ~all Or the pla~form centrally Or the wicth thereor. An index illuminating lens 76 is located in the passa~e l~ zn~ serv2s ~o concentrate the li~h emit~ed through the passa~e 74~ Ac; w 11 be described nerein~e-, li~ht emitted from tne lens 76 passes through t~e indexin~ ri~
4G and serves to provide 2 method Or locating â required locc ion o~ tne microriche by reference to the illuminated grid.
T~ BASE i~MBER
The base me~ber 14 has a bo~tom wall 80 (Fig. 2a) ex-tending from the back face thereof towards the rront face. An angularly inclined bottom ~all 82 extends upwardly and forwardly from the bottom wall ~0 to a front l.~all 86 which extends vertically up~ardly to the platform 66. An inner wall 88 extends upwardly fro~ the platrorm and a top ~Jall 90 extends rearwardly from the inner wall 88 to the bacl.~,Jall 93. A~air Or guide ra ls S2 are located on the inner ~ace of the bottom wall 80. A
plurality of vent openings 94 are located in the bottom wall 80 and in the inclined bottom wall 82. An operating switch 95 is mounted in the front ~:all 86. Vent passages 96 are located in the platform 66. A condenser passage 98 opens through the plat--form 66. Air circulation passages 100 and 101 open through the top w211 90 and back wall 93 respectively. A lamp mounting passage 102 opens throu~h the back wall 93 Or the base.
A removable dra~Jer 104 is proportioned to extend through the passage 102 in the back wall so as to be located within the base 14 with the back plate 106 thereof closing the passage 102. The drawer 104 has a bottom wall 10~, the opposite side ed&es of which are adapted to fit within the track formed by the ~uide rails 92. An electrical plug member 110 is located ~t ~nD in.~r D~ 0~ t'~D ar~:~e~ 2~ t~
a soc~e~ 112 locate~ in ~h& G~S~ e~ D '~'~T~ S Ocâ~ed in an o~osite ~os~ ~on ~ t~e b2se. h ~refocusse~ 1~J ? _1L
_s 2~u~cbl~ ~0~ D '~ O ~; ~ ~ ' ~ V ~ ~ ~ ~ ... . G ~ ' j - r G ~ - C _ _ moultir~ bolt 115 ~:?hich is threadea an.à :h~ch e}: cncs -hrc_~^. ^-p~ssaOe 116 in ~he bot~ori-~_ll 10~ and is clæm~e~ b~ ns c~ -nut 11~ and a spring ,:asher 120.
The lamp 114 and its associated hous'ng ~ay be r.ovec longitudinally Or the bottom wall 108 to any regu~red ?osi~ior.
1~ The lamp 114 is electrically connected to the plug member 110 by wires 122 such ~hat when the dral?er 104 is located in an opera-tive position within the base, electrical po-^~er is supplied to the prefocussed lamp 14.
The electrical power is supplied to the microfiche reader as a whole by means Or cable 126. The electrical power is suppl1ed to the trans3~0rmer 12~ which is located in the hous-ing and the trans~ormer 128 is electrically connected to Ol~/OFF
switch 95 by l~nes 130.
HOOD STR~CTURE
The structure of the hood 12 is illustrated in Figs. 1 and 3 of the drawings. As shown in Fig. 3 Or the drawings, the hood 12 has a pair 03~ side walls 132, a top wall 134, an upper ;back wall 136, a lo~ler bac~ wall 138 and a bottom wall 140. A
passage 142 opens between the lower back wall 138 and t~e bottom all 140. A screen support shoulder is formed about the ~nner edge of the passage 142 and consists of side shoulder portions 144, top shoulder portion 146 and bo~tom shoulder portion 148.
A pair of support lugs 150 (only one shown) are located at the lower edge of e~ch side wall 132 and serve to support the lens support plate 40 as will be described hereina3~ter. The bottom ~%~

~211 ~ s fo~m~u ~iitn a ~luralit~ of a~r circul~t- n~ ve~
- ~2ssages 152. The hood 12 is mounted on the base 14 with tne bolto,m ~all 11'0 su?ported by the top wall 90 of the base.
.'our.'in- screl;s 1~ secure the hood with res~ect to t'n~ base.
~ .nGAw moul~-ir.g l,p 155 is located at 'he rront ^.dge of the ihoc~ to secure a -~;indo~-: 15~ therein. Tne screen 15 has ~ounf~nE
passcgPs 1~0 ~ . c~ in vhe bac`~ fac2 thereol wh~ch are t:hred-ably en~aFed by mounting scre~s 162 (Fig. 3) which extend through pass2ges 164 formed in the upper screen mounting shoulder 14c to secure the screen ~Jitn respect to the housing in the position . showr. in chain lines in Fig. 3. A highly reflective mirror 166 :l is mounted on the inner race.of the top wall 134 of the hood to -reflect ima~es projected thereon onto the screen 1.
` SCREEN
Tne screen 16 is made rrom a ~tary body of molded plastics material such as A.B.S. . The image receiving surface 166 Or the screen has a concave spherical ; curvature. The side edges 168 of the screen converge with respect,to one another in a direction towards the upper edge Or

3 the screen. It has been found that the configuration of the image receiving surrace achieved by providing a concave curvature both longitudinally and transversely of the.screen and by re-ducing the width of the screen towards the upper en~ is most suitable for receiving images projected b~ the projection system described hereinafter. The unitary body of the .~creen 16 includes side walls 170, top ~Jall 172~ bottom wall 174 and a ~air of diagonally extending reinforcing webs 176. The inner edge Or the side w211s is sha~ed to follow the configuration of the hood in -.
which it is mounted. The image receiving surface 1~6 Or the screen is plated with a la~er of sil~er or the-li~e to form an image reflecting coating thereon.

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L~ ASS_.i~`~
The l~ns asse~ 2~ is illuc~trated in ~i~s. 3~ 4 2..d 5 of tne ara~.~in~s. Tn~ lens assembly 2~ consists Or a sup~orv plate - 40 .~hiC~! is mou~ted G~ su?~ort lugs 150 of thC hood ~ ~c~s Or mounti!lg scre~s 180. Tne supporv platP 40 has z p2ss2re lc~
ope.in~ tnerethroug;~. hs sho~n in Fig.s. 3 and 4 o~ t~e dr2~nrs~
a su~orv rail 184 is locaved ~elo~.~ the side eQges of the rz~s~e 182 in 2 space~ relationship l~ith respect to the .support plate 40.
A slide member 186 has a central portion 1O8 ~Jhich ~ substanvially 10 shorter in len~th than the passage 182. The slide ~em~er 1&6 also has a pair Or en~ portions 190 which are thinner than the central portion 188. The slide member 186 is mounted in the support plate 40 and is supported therein by supDort rails 184. The central portion 188 of the slide member projects into the pas-sage 182 and the end portions 190 underlie the support plate 40 at opposite ends Or the passage 182. By reason of the fact that ~ the cent~ral portion 188 is shorter than the passage 182, the - slide member 186 may be moved back and forth in the passage 182.
The front support rail 184 has a notch 192 opening therethrough ~lhich serves to operably locate the required objective lens in the pro~ectlon path as will be described hereinafter. The slide member 186 has a pair of tubular sleeve pro~ections 194 projecting downwardly thererrom. The sleeve projections 194 have passages 196 opening therethrough. A longitudinal slot 198 also opens through each sleeve projection at the front end thereof, a por--tion of the slot 198 also opening through the central portion 188 o~ the slide into the passage 196. A pair Or lens holders 200 ; are adapted to fit within the passages 196. Each of the lens ; nolders 200 has a key pro~ection 202 extending longitudinally ~ 30 thereof. The key 202 has a llp portion 204 at the upper end ':

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V~3~ j ~ erQo~ .:h~c:~ ~rojects out~?~rdl~ froJ~ t:~e ~,~in oi~. T~Q ~ ln ~ody of the `~e~ 202 is caa~ted ~o fit ir. e close f~'tinC relation-shi~ ~ithin tne slot 198 so t:nat the lens holàer mQ~.ber 200 may dro- ~o~-,warQ'y throu~n the passa~e 1~' .;1~D n t'n~ ':e~ por'-cn 202 is aliFned ~:~itn the notch 192 in 'he s~pport rails 1~'' of ~..e sup~ort plate 40. ';'her. the ~e,l 202 -Is cu' of a~ nment ith 'he notch lg2, the lip ~orvion 20~ rides alon~ the support rail S~
ar.d holds the lens holder in a raised posi~on. Objective lens~s 206 and 207 are threadably mounte~ in tne lens holders 200.
iO The objective lenses 206 and 207 have a housinF 208 ~:lhich has a greaver diameter than the diameter of the passage 196 ln the slide member 186 so that the housings 208 limit the extent to ~lhich the lenses may drop relative to the slide member 186.
PROJECTIO;~ SYSTEM
- The image pro~ection system is illustrated in Fig. 7 of tne dra~ings. Rs shown in Fig. 7 of the drawin~s, light emanating from the prefocussed lamp 114 travels along the path 210 and is reflected by a first cold mirror 212 which, as shown in Fig. 2 of the drawings, is moun'ed in the demountable drawer 104. Tne light is rerlected by the mirror 212 along the path 214 to a condenser lens 216. The condenser lens 216 is mounted in the passage 98 formed in the ~latrorm 66 of the base 14. The light beam passes through the condenser lens 21b and is directed along the path 218 throu~h a portlon of the microfiche 4IJ. The image carried by the mlcrofiche 44 is proJected through the ob-~ective lens 206 along the path 220 onto the first surface. ~irror ,i 165. The image is reflected from the mirror 165 along the path 222 onbo the image receiving surface 166 of the screen 16. The lamp 114 illuminates the interior o~ the base 14 and the light from within the base is emitted throu~h the index illuminatin~

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le~ns 7~i 2-~ O`',G ~r-e pa~ 4 ~hic-J proJec~s 'hrou~ the in.~e~: ~rid 46. ~ re2so-, of tne fact thât ~he incex erid ~6 2na microfiche ~ are ..ourl~eù i~ the combinoù m.icro~-c:~e c2r~ a~e an~ index hol~er ~ ~ ~ d rel~tions'~ir li r,;~ respec~ ~o one another ans the f~ct 'h2t tile i~de~: illumin2tinc~ ~e2~ Or l ~ht tra-~Tels 21c-ir ~ p~ti~ 22'' nic~ is locz'ed in z ~ixed relctionsh~p ~7ith respect to the path 21~ of the microfiche illuminating li~ht beam, it is possible to locate any required portion Or the microficne in the projection ~ath by locating the correspondin~ portion of the index ~rid in the in~e~ illuminating path. The slide member 190 is movable so as to permit either one Or the ob~ective lenses 203 to be located in the path 21~. In use, the objective lenses 203 may have difrerent magnifications so that the magnification of tne microfiche reader may be adjusted by the simple act of moving the slide 190 to and fro to align the required objective lens with the image proJecting path 218. Similarly, the carriage 18 is movable relative to the cordenser lens 216 in the direction of the X-axis and in the direction of the Y-axis shown in Fig. 7. This mobility of the carriage 18 permits any portion of the microfiche 44 and index grid 46 to be located in the paths 218 and 224 respectively so that any portion o~ the microriche 46 may be projected onto the image receiving sur~ace 166 of tne screen 16.
OP~RATIOI~
Prior to operation Or the micro~iche reader, the re-quired ob~ective lenses are selected. The optical characterist~cs Or the ob~ective lenses may be such that it is necessary to ad-~ust the position o~ the prefocussed lamp 114 ~rith respect to ~he condense:- lens 212 in order to rOcus the beam emitted from the condenser lens 216 on the ob~ective lens 207. As previously . -15--~ ic~'ed, the Frcfocussed lar;~ is adjustable !~n respecv vo the drG~/er 104. The ~osition ol the prGrocussed lamp 114 is, therefore, ad'u~ted by r~leas~F t~e cla~?~ nut 118 2nd ~ovi~, v:~e la..~ 114 lo~r-vu_~ all~ Or t~e bottom ~.all 108 o~ ~he dra~e..
I~ order to loc2te the mi(:rofiche 44 in the microfich-holder 1~, vhe microfiche holuer 1~ is moveo in the QirQct~on Or '.
X-axis (~ig. 7) until t:~e up~er glass flat 30 is elevated by engagement of the actuator li~ 36 ~.~ith the tongue 38 l~hich ?rovecvs do.~n.Jardly from tne support plate 40. Tlle microfiche 44 is ther.
located between the upper and lo~:Jer glass flats 28 and 30 and the carriage 18 is moved inwardly, as a result of which the unper glass flat 30 is lo~Jered into a face-to-face relationship ~rith the microfiche 44.
As previously indicated, oneof the objective lens mem-bers 208 is aligned tYith the path 218. Tne lens holder 200 of the aligned objective lens rests on the u'pper glass rlat 32 while the lens holder of the non-aligned objective lens is held in a spaced relationship above the upper glass flat 32. When the lens , hold'er 200 is aligned with the projection path~ the key 202 and lug 204 are free to slide in the notch 192 in the support rails 1~4. By reason o~ the ~act that the lo~er end of the aligned lens holder rests on ~he upper glass flat~ the distance between the objective lens and t~e microfiche 44 is a constant and conse-quentl.y the ob~ective lens can be accuratel,y located with res-pect to the mlcrofiche and li~ith respect to the image receiving sur~ace 166 Or the screen 16.
When the microfiche is operably located in th~ micro-fiche nolder 1~, as described above, the microfiche holder 18 ~ay be moved to align any required portion Or the index grid ~Jith respect to the index illuminating lens 74. The beam of light .

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e~1~teù throu~,'n ti~e illum1~ati~g le~s 74 ~;lill il um~:.cte ~:~e sec~ion of tr,e grid corres~ondirg to the portion of t:~e r.icro-ficne which Drojecte~ onto the screen. In this m2rne~, any re-~uircd ~or~ic-. of _'ne microliche m2y be projecte~ o~.to the scre~~
oy reference ~o the illumin2ted section of the inde}: gr~d.
S~ ;A~Y
Frcm tne roregoing it will be apparent that the micro-fiche reader described above provides a number of improvements over the l.nown structures. In one such improvement, the micro-fiche reader pr~iàes a combined microfiche carriage and index holder 18. By reason of the fact that both the microfiche 44 and the index grid 46 are mounted in a fixed relationship with respeci to one another, it is easier to accurately locate the required section Or the microfiche with respect to the illumin-ating path. In addition, the undercarriage support structure ror the combined microfiche carrier and index holder is desi~ned to provide free movement Or the carriage 18 with respect to the pro-jection path. The V-shaped profile of the guide rails and sup-port wheels is such that there will be a minimum backlash in the guide track system. It will also be noted that by reason o~ the fact that the microfiche is retained in a stationary relationsnip with respect to the index grid, any backlash in the undercarrl2&e support system does not contribute to any misalignment of the mi-crofiche with respect to the ~rid as would be the case in a structure where the microflche is move~ relative ko the grid. TA~
, fact that the upper glass flat is elevated automatically when the, carriage 18 is move~l to a predeterm~ned forward positlon greatly i facilitates the removal and placement of the microfiche between the upper an~ lower ~lass flats.
A further improvement is provided in the structure Or t 02~i tr~c ~ ~~J~ G_~r'...`~ ., t'l~- a ~se~ V ~ ~~o~ l e,r~ C~m;;~
eitncr on~ Or hicn m~ be moved 1--vo ti~c p~c~e~ion ra~ as r c' v v ' ~ G ~ , v ? - 'e-s ~s~ ccc~, c~ lr v _ O;~ _ _V~ _e~s .-v__- vo r c S _ O . v : c ~ , _ u---e~ c ''~at~ t:-~re~y positivel~ :loca'~ the O~ eCt~Q 12-~s il: 2 set pc~iv on .i-h respect to the microriche.
i sti ; ~urther m~rc-ement plo~ride~ ~y th~ .,,icro~ c.e reader of the ~referred embcdimer.t is in t-e s'.ucture o~ the ~ro j ec ~ ion systQm which includes a Q~mO'1:1~2~l e ~odul 2r unit 1~4 which supports a prerocussed lamp for movemert thereon SC! tnat the lamp may be moved towards and away rrom the condQnser lens whereby the optical system may be ad~usted to accommodate objec-tive lenses having dilferent characteristics. This provides lor a very simple adjustment of the optical system which is not available in exi~ing microriche reader devires.
A still rurther improvement provided bv further features of the microfiche reader is in the projection system which includes a prefocussedlamp, a rirst cold mirror~ an optical condenser, an objective lens, first sun~e mirror, and a viewing screen, all of whicn are mounted in series along the projection path. The viewing screen is formed from a unitary body of molded plastics material and has an ima~e receiving surfâce formed with a concave spherical curvature. The concave spherical curvature of the i~age receiving surface provides ror the minimum dis-tortion of the pro~ected image.
Yet another advantage Or the structure Or the micro-~iche reader of the preferred embodimenb is in the fact that it is not necessary to provide a forced air co~ling system in order to cool the projection system. The prefocussed lamp is prerer-ably a ninety watt lamp. The base ~e~ber is formed with a . -18-2~6 plurality of ventilating passages 94. The base member 1~ is supported on feet 81 so that it is spaced above its support surface in use so that air may be admitted through all of the ventilating passages 94. The air passes upwardly through the base and a portion of the cooling air may be discharged from the base through ventilating passages 86 in the upper wall of the platform 66. The remaining portion of the cooled air, which is the major portion of the air, is discharged from the base through the passages 100 in the upper wall 90 to pass through the passages 152 in the bottom wall 140 of the hood and to be directed rearwardly from the hood through the passage 142 in the back wall of the hood and thus to atmosphere. It has been found that this air circulating system provides adequate cooling for a ninety watt rated prefocussed lamp 114.
Furthermore, it has been found that this cooling system sufficiently cools the entire housing of the microfiche viewer to an extent that the viewer may be made entirely from an in-jection molded plastics material such as that identified by the Trade Mark MERLON SF600 structured foam plastic.
By reason of the fact that all of the various components of the viewer housing and carriage may be made from injection molded plastic material t the overall cost of production of the microfiche viewer can be minimized in a mass production process.
These and other advantages of the microfiche viewer of the present invention will be apparent to those skilled in the art.

Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A microfiche reader having a housing, a viewing screen located within said housing and a projection system for projecting an illuminating beam of light along an illuminating path, said illuminating beam being directed through a condenser lens, a microfiche and an objective lens arranged in series and onto said screen, the improvement wherein said projection system includes (a) a demountable modular unit comprising:
(i) a frame removably mounted in an operative position in said housing, (ii) mirror means mounted in said frame in a fixed position with respect to said frame,said mirror means being located in said illuminating path when said frame is in said operative position, (iii) a prefocussed lamp mounted in said frame for movement towards and away from said mirror means to vary the length of the illuminating path between the prefocussed path and the condenser means whereby the optical system may be adjusted to accommodate objective lenses having different characteristics.

2. A microfiche reader as claimed in Claim 1 wherein said prefocussed lamp is rated at less than ninety watts and said mirror means is a cold mirror and the focal length between the prefocussed lamp and condenser lens is no more than eight inches and the housing is vented to permit free circulation of air whereby said reader may be cooled without the aid of an air circulator.

3. A microfiche reader comprising, a housing supporting a single optical condenser, a microfiche carriage, an objective lens support and a first surface mirror and a screen in series alignment with a projection path extending through the condenser to the screen, said objective lens support being adapted to releasably support any one of a number of objective lenses, a lamp support frame adapted to be removably mounted in said housing so as to be releasably retained in an operative position, a cold mirror and a pre-focussed lamp mounted on said frame so that the light emanating from the prefocussed lamp is reflected by said cold mirror along said illuminating path when said frame is operatively located in said housing, said prefocussed lamp being mounted on said frame so as to be movable relative to said frame between at least two positions spaced from one another along said path to accommodate objective lenses of different characteristics in use.

4. A microfiche reader as claimed in Claim 3 wherein the prefocussed lamp is rated at less than 90 watts and the focal length between the prefocussed lamp and the condenser lens is no more than eight inches and the housing is vented to permit free circulation of air whereby said reader may be cooled without the use of an air circulator fan.