DE3330783A1 - Overhead projector operating by a reflection method - Google Patents

Abstract

The invention relates to an overhead projector operating by the reflection method, which consists of a base plate holding the mirrored Fresnel lens, and an overhead housing, which is carried by a support arm mounted on the base plate and in which the light source and the lens are accommodated, over which a deflecting mirror is arranged which can be pivoted about a joint and simultaneously serves as lens cover. It is the object of the invention to configure the overhead projector for small sizes of original and operating by the reflection method, in such a way that the previous optical disadvantages and the disadvantages occurring due to the relatively large size of mirror are quite decisively reduced. This object is achieved due to the fact that the light source is arranged on the side of the lens averted from the joint of the deflecting mirror, and that in the folded-down state the deflecting mirror or the holder of the deflecting mirror reaches beyond the light source.

Description

DiPL.-PHYS. DR. WALTHER JUNIUS 3 Hanover

WOLFSTRASSE 24 TELEFO N (05 11) S3 45 .'0 ^ g AUffUSt

Dr.J / SH My files;

GtebH & Co.KG., Vlesenstrasse 3 * 6070 Längen

In ReflLesdLonoverfahren working overhead projector

The invention "relates to an overhead projector that is reflective of the types of testing _& consists of a spiked fresnel lens that is installed in a Sragarai housing attached to the base plate, in which the idcntfuelle - and the lens, among other things, are placed . _# üt> he which a deflecting mirror is arranged _t the taia a Qelenk. is adjustable and serves as an object barrier at the same time *

Orsrliead projectors of this kind, which work in the RefXeslons Voraksrea, create a broader market in all of them, because they do not instruct the raisa-needy with the in ± hs uatergsbraclitea Mcslitquelle, which is for the other kind of. Overleadproäektoi ^ iip who work in the JDurcmic & irTerfaliren »is necessary» The arrangement of Idchtq [u © lle 9 lens in a common Oyerli sad housing above & fresnel lens aat the disadvantage that with the hitherto common arrangement in which the light source from Jrojisis is added of the lens liegjf ^ __ alsö "" ätif the deia joint of the IMLenkspie.g@ls-sitgewiuidten side of the object

the optical path of rays looks ideally as with the iss Burchliohtvör ^ ahrea. working overhead projectors. With either of the Kittelstrahlengasg of the light source © the middleXstraalengang of the lens niob * in the dmrch the middle of the Fresnel lens passing through geesäetrisehsn axis © the »Prssnelllens lie, including the resulting projection errors sn veraiadem, 2atg.12 lXe as the d © a of the object outside the gecjaetrisdh.a Aolise of the! Fresnel lens an »■ and was mostly at the same angle of deviation Sas sees siaca see that the dimensions of the mirror are somewhat broader. This deflecting mirror is trapesf ^ naig, among other things, in particular its läagore baseline is chosen to be larger. In the case of ChrerheadprsjelctQren £ Vkr the proä © kti © n of templates in the G-size ΊΠΜ A 4 si & d the deviations - and occurring pehler a © c3i small »Bs is kama sa iaerlcen that the deflector is somewhat larger and it is also kaim su mrlzen ₉ characterized in that the lens is aageordnet so that the _e! ■ iittelstra & l of v <m Vsrspiegel the SNG of Iresnelliase rönektierten Liehts imter eiaea small angle spitsen sur optical Aehse the lens diareh this hindtirchtritt. Eas will be different after _$ as soon as overhead projects are built for the fögektisa of smaller publishers, because here lens © ait -umso Kuvzsrer focal length must be used, the smaller the sub-pregisierende template is. In ia ^ Re-ddeslcasvariahrsn working Overheadpro j ektoreji for this klainen Vorlagsfoniate to hei the previously fcenntsten Anordznmg the light source ia Ovsrheadgehäase on the Deia joint of the string of the lens tSaienkspiegels sugewandten seigen striking the discharged disadvantages.

These unrelated parts cannot be eliminated by the fact that

_mm X _m ^

stan the lens rüokt more in NMhe the optical axis of Sresnellinise because then the beam path of the light source is farther from this Achs® and Auslauchtuag is considerably worse.

Then the smaller the fonsat, the larger the larger of the Usalenkspiegel have the only disadvantage * that the larger mirror looks unSa, but also the one Disadvantage »that this mirror is now far above the lens OJid therefore stands out in the case of siransporting the overhead pro ^ efetors The way is tjmd therefore also be damaged: can"

The present invention avoids these disadvantages strikingly simple way

Ss is the atifgab © of the ib? Fiadtmg, which in the Beflesi ons procedure working overhead projector for! your original backsate s © sa design »that the previous optical Fachteil® and which disrch the larger mirror format ^ Q ' the laughable parts of gaas are considerably reduced

The JSärfindiisag Daria is ^ that the light source on the öelenk of I & ilenksplegels side facing away from the Obwalden ^ elctivs is arranged and the deflection mirror bsw · the ISslenkspiegelhalterung in the folded-down state of time reaches over the light source ·

Seen from Pro visor Ender from ver the lens - - This Anortaag the I & ohttpielle is the optical path ia lens better and dia dimensions of UmlenkspiegelE may be somewhat smaller · Since the deflecting mirror across attacks in the folded-down state over the light source, it is in iüransportstellung in a

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such an arrangement that it does not or hardly over the edges protrudes from the lens housing and is therefore not damaged during transport *

It is useful if the holder of the steering mirror is designed as a single cover for the lens and light source. In this way, a dust case is the _lens's avoided but also a dust case to the light source not only for the storage of the overhead projector. Such dust is sometimes noticeable with an unpleasant burning smell,

It is advantageous if you have a scattered light failure the source of light avoids the fact that the light source is covered upwards by a double-layer grill, one layer of lamellas to the front and the other Position of slats is straightened to the rear if you have it does not prefer to cool the light source with a fan that cools the heated air out to the side blows out of the overhead housing.

The essence of the invention is shown below with reference to an exemplary embodiment shown schematically in the drawing. explained in more detail »Seigen:

Fig «1 eii: .e side view of the overhead projector,

Fig. 2 a side view of the overhea & housing in enlarged view,

3 shows a cross section through another Ovsrhead housing.

At the Platts Grind 1, in which the Fresnel lens is mounted verspisgelte ₉ whose surface 2 as the support for the product to profiting film and as a writing surface is _p, the support arm 3 is mounted, wherein the overhead housing

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4 carries · The lens is in this overhead housing 4

5 and the light source 6 with the lamp 7 housed. At the top, the light source housing 6 is closed off by the grill ι 8 _# 9 * With grill 8, the lamellae are directed upwards and forwards, and with grill 9, the lamellae are directed upwards and backwards.

Above the objective 5 is the T-steering mirror 10, with which the light rays 11 emerging from the objective 5 are deflected onto the Brejelrfeionwand. This TMLen & spIegaL 10 is attached to a hinge 12 on the overhead housing 4 and can be folded down with its holder 1 into the position shown in dashed lines.

The light source housing 6 is arranged in the overhead housing 4 in such a way that it is on the dea joint 12 for the. Deflecting mirror 10 is arranged facing away from the side of the lens 5 * The deflecting mirror 10 BSW. the steering mirror geMuse 13 serves as a common cover for the object 5 «ad the light source 6.

Another overhead housing is shown in Pig · 3 . Here, the fan arranged behind the air outlet slots 14 not only sucks in air through the air inlet duct 15 around the ropes of the shredding device, which are housed in the vertical part of the cantilever arm 3; too cool © n _s but also air through the air inlet slots 16 on the face of the overhead housing. This cooling air sweeps past the lamp 7 and is sucked into the horizontal part of the support arm 3 through the air ducts 17 »18, which are formed between the lens 4 and the string walls 19 of the housing. This cooling air is then also conveyed through the Luftauslaßöffnun "gen 14 from the befindli in the inclined part of the support arm 3 fan.

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Claims (1)

Expectations: 1. Ia IteflesdLoasverfahren overhead projector, consisting of a sealed! Fresnel lens holding ßEndplatte -and an iron of a »Eragarza mounted on the GarstndpXatte! Eragarza worn Gverhead housing * tXL which the light source and the lens are housed, over xfelchem a mirror is arranged _for the tm a joint can be pivoted and serves as an objective cover on the same side, thereby g © kexmseichnet _ff that the light source (6) on the hinge (12) of the U & enlispiegelä '(10) äbgekenrten side of the lens is ordered az d ite &, ^ he -Xfeilenlcsriegel (10)' bsw, dia To lenlrspiegelhalterung (13) ± m folded-down state iXber the Iiiehotiaelle (6) grabbed 2 * overhead projector j ^ ch claim 1, characterized, that the holder (13) of the üsaenkspiegöls (10) as common Äbäeclomg for lens (5) -and light source (β) is formed « 5 · Overhead projector according to claim 1, - ^ * - dadtxrch gekennseiahnet * ^ i ^ " that the light source (6) is covered after ohen by a double-layered Orill (8 ₉ 9) * one layer of which (8) from Ifa & ellen to vom and its other location (9) of slats is directed backwards. . ι—, -tr 4. Overhead projector after. Claim 1, characterized, that in the overhead housing (4) on the side of the O "b;) ektiYS (5) awir-uslien this and the side walls (19) air ducts (17,18) are formed »by the cooling air from the Mchtquallengahäuse (6) in the Sragana (3) or vice versa "is moved. copy