US 3580685 A
Description (OCR text may contain errors)
United States Patent 4 24447X QHHHQHM 5555555 9999999 9 "mmmm "m n am 0.1 5 "8 6 amm fiadm u bt oa m ear HBSSMPCG 72266530 68890256 88889999 11111111 11 2 83 11111 11792256 82904760 y w w 77838889 66673542 22585 39 122 M n mw sl w a m n m m WFB MN. 0 0 m 9. n a U070 am.m G J7NM L r. 0. de m mm 6 Munwm m p aww I AFPA 11]] 2 253 7 2247 [[[Il  MEANS FOR EXPOSING NORM COVERED Primary Examiner-Ronald L. Wilbert PLATE WHILE MOVING IT TO EX Assistant Examiner- Warren A. Sklar SITUATION Attorney-Ira Milton Jones 4 Claims, 6 Drawing Figs.
specimen plate is slid out of moving into the isolation ge, and is slid back into the cover as it is moved out of the isolation chamber.
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' sum 2 or 3 pd E siavflag arErzkssun the specimen plate substantially simultaneously with its removal from the isolation chamber.
An example of one type of isolation chamber with which the apparatus of this invention has utility is disclosed in the copending application of B. O. Lindahl, Ser. No. 633,124, filed Apr. 24, I967, assigned to the assignee hereof which relates to means for determining the cleanliness of air in a socalled clean room. In a clean room, which is a controlled environment enclosure wherein high-precision instruments are assembled, it is customary to monitor the cleanliness of airby .exposingla slide or plate for a certain interval and then checking the. dust accumulation on the slide to obtain an evaluation of the amount of dust presentin the air of the clean room.
According to the teachings of the. Lindahl application, the slide has a perfectly flat, black-top surface, and the isolation chamber in which it .is examined has means associated therewith for directing light across the top surface of the slide,
parallel thereto, from one or more directions. The clean surface of the slide itself, being flat and black, reflects none of-the light; but every dust particle on it reflects a smalltbeam upwardly from the surface. The isolation chamber therefore has in it a photosensitive element and a lens, and the beams reflected upwardly by the dust particles. are focused upon the photosensitive element by means of the lens. The responseiof the photosensitive elementaffords a measure of the amountof dust collected on the surface of the slide and hence of the quantity of dust present in -the air of the'clean room during the interval that the slide was exposed.
Such an inspection device, comprising an isolationchamber and its associated optical and measuring equipment, constitutes a rather expensive and delicatepiece of apparatuspso that in a plant having more than one'clean'room (as is often the case) it is not practical to provideaatseparate inspection device for each clean room, nor to *movetthe device about from one clean room to another for inspection of the slides exposed in each. On the other hand, to carry'an exposed slide out of the clean room and through portions of the plant that do not have a controlled environment, in order to take itto a central inspection device, would subject the slide toa substantial dust accumulation that would invalidate the inspection results. 7
With the foregoing considerations in mind, it is the general object of this invention to provide, in combination with 'an isolation chamber such as that in an inspection device of the above-described character, a cover for protecting a slide as it is carried to and from the isolation chamber, and means for readily moving the slide to and from a; predetermined situation in the isolation chamber, for automatically uncovering the slide as it is moved into the isolation chamber, and for automatically restoring it to its covered condition as it is withdrawn from the isolation chamber.
With these observations and objects'in mind, the manner in which the invention achieves its purpose will be appreciated 1 parting from the invention.
The drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:
FIG. 1 is a perspective view of an inspection device for determining the amount of dust that has been accumulated on a specimen plateexposed in a clean room, with portions of the device broken away to show details of its construction and a specimen plate situated in it for inspection;
FIG. 2 is a perspective view, on a larger scale, of a typical specimen plate with its cover, a portion of the cover being shown broken away;
FIG. 3 is a vertical sectional view through the inspection device, showing the carriage in position for placement of a covered specimen plate thereon and for removal of the same therefrom;
FIG. 4 is a view generally similar to FIG. 3 but illustrating conditions that obtain during movement of the specimen plate to its situation for inspection in the inspection device;
FIG.'5 is a view generally similar to FIG. 3 but showing conditions that obtain during withdrawal of the specimen plate from the inspection device; and
FIG. 6 is a group, perspective view of the specimen plate and its cover, the carriage and the cover holder.
Referring now more particularly to the accompanying drawings, the numeral 5 designates generally an inspection in general, a housing having a front wall 7, a rear wall 8, a top wall 9, a bottom wall 11 and opposite sidewalls 12 and 13. In-
side the housing, cooperating with the top and bottom walls 9 and 11 and with the front wall 7 to define an isolation chamber, are a rear partition wall 14, which extends parallel to the front and rear walls and is spaced from them, and a pair of side partition walls 1-5 and 16 which are spaced from and respectively parallel to the sidewalls'l2 and 13.
It will be understood that the inspection device 5 is merely illustrative of a type of isolation chamber means in which a specimen plate is intended to be exposed and to and from which the specimen plate must be brought in a covered, protected condition.
Within the housing, tothe rear of the isolation chamber, is a light source 17 whichsends a beam of light directly through a slotlike aperture 19 in the rear partition wall, across and parallel to the top surface of the specimen plate 6. By means of obliquely arranged mirrors 20 and 21 in the housing, another portion of the'light emitted from the light sourceis directed through a slotlike aperture 22 in the side partition wall 16, likewise across and parallel to the top surface of the specimen plate 6 but at right angles to the beam that comes directly from the light source.
Light will be reflected upwardly only by dust particles on the inspection'plate, and such upwardly reflected light is concentrated upon a light-responsive element.23, located above the specimen plate, by means of a lens 24 that is between the specimen plate and the light-responsive element. In this case the light-responsive element 23 is illustrated as a sensitive photoelectric cellconnected with an amplifier 25 in the housing, and the amplifier is in'turn connected with a meter 26 that is visible at the exterior of the housing and can be calibrated in terrris of number of dust particles.
The "photoresponsive element 23 and the lens 24 are mounted in a suitable holder to be carried on the free end of a swingable arm 27 which projects from an upright rotatable post 28. A lever 29, anchored to the bottom of the post 28 and projecting through the front wall 7 of the housing, provides for rotation of the post 28 to swing the photoresponsive element and lens between the operative position shown in FIG. 1 and an inoperative position well 'to one side of the axis of a microscope 30 that is mounted in the top wall f the housing. The microscope can be used for visual inspection of'ilust particles on the specimen plate, so'that the nature of anyzcuntamihan tspresent in the air of the clean room can be ascertained.
The specimen plate 6 can comprise a rectangular tray 31, havihg a shallow rectangular depression in its top surface, and
a slide 32 which fits'closely in the depression and which has a suitable top surface. For protection of the specimen plate at times when it is not. intended to have it exposed, it is provided with a removablecover 33. The cover has a medial portion 34 that is adapted to overlie the slide 32, and has opposite marginal portions 35 that are channel shaped, opening toward one another, for slidingly engaging opposite marginal edge portions of the tray 31. Thus when a specimen plate is picked up in a clean room, it and a cover 33 are immediately slid lengthwise into assembled relationship so that the cover protects the specimen plate from further accumulation of dust en route to the inspection device.
' The inspection device has means, generally designated 37,
. for receiving a covered specimen plate at the exterior of the housing 5, for removing the specimen plate from the cover while moving it into the situation in the isolation chamber that establishes it in the proper relationship to the light apertures l9'and 22 and the optical apparatus 23, 24 and 30, and for replacing it in the cover while withdrawing it from the isolation chamber back to the exterior of the housing.
In general, said means 37 comprises a carriage 38 which is constrained to motion in opposite directions into'and out of the housing through an aperture 39 in the sidewall 12 and an aligned aperture 40 in the side partition wall 15, and a cover holder 41 whichis so mounted on the carriage that it can partake of a portion of such in-and-out carriage motion but can also be confined against motion at certain times without interfering with the remaining movement of the carriage. The cover holder 41, as explained hereinafter, detachably holds the cover 33 of a specimen plate, while the specimen plate rests directly upon the carriage and is constrained to move therewith.
Specifically, the carriage 38' comprises a rectangular platelike body member 43 having a reduced thickness, as at 44, along each of its longer marginal edge portions, to define a raised central portion which has a width about equal to that of a specimen plate and uponwhich a specimen plate is adapted to rest. Attached to the front end of the platelike body member 43 is ahandle 45 that projects above and below the body member. A pair of guide rails 46 extend rearwardly from the handle through and beyond a downwardly projecting flange portion 47 onthe rear of the body member 43. The handle 45 and the flange portion 47 cooperate to hold the guide rails 46 parallel to one another and to the longer side edges of the platelike body member, and the rails 46 are. slideable in inner and outer bearing brackets 48 and 49, respectively, that'are secured to the bottom wall 11 of the housing and project upwardly therefrom, The inner bearing bracket 48 is with the outer bearing bracket 49 to define the outer limit of carriage motion.
The cover holder 41 has a flat platelike body portion 50 that flatwise underlies the body portion 43 of the carriage, and it has upwardly and inwardly projecting opposite flangelike marginal portions 51 that engage around the reduced thickness marginal edge portions 44 of the carriage body member 43'to connect the carriage and the holder in a manner that provides for relative lengthwise sliding motion between them. Projecting upwardly from each of these flange portions 51, near the front and rear ends of the cover holder, are fingers 53 that engage the opposite longitudinal side edges of a cover 33 to readily detachably secure it to the cover holder. Other fingers 54 on the cover holder, projecting toward one another across the top of the body portion of the carriage, engage the front edge of the coverto locate it relative to the cover holder and confine it against forward displacement relative thereto.
The body portion of the cover holder has an inward projec' tion 56 that terminates in a downwardly projecting flange 57.
The flange 57 cooperates with the outer bearing bracket 49 to define the outer limit of motion of the cover holder, in which a cover thereon is wholly disposed just outside the sidewall 12 of the housing. lnasmuch as the aperture .40 in the partition sidewall 15 is just large enough to clear the carriage and a specimen plate thereon, the inner edges of the inner upright fingers 53 on the cover holder, and also the front edge of the cover thereon, engage the front surface of said partition wall to define the inner limit of motion of the cover holder.
For loading with a covered specimen plate, the carriage is of course situated in its outermost position, illustrated in FIG. 3. As the specimen plate is moved flatwise downwardly onto the carriage, its cover 33 engages between the upstanding fingers 53 on the cover holder, and an upwardly projecting pin or boss 58 on the body portion of the carriage engages .in a closely fitting hole 59 in the tray 31 to constrain the specimen plate to motion with the carriage.
As the carriage is then moved inwardly, a point is reached where the cover holder and cover plate are brought into engagement with the side partition wall 15, as above described, and the cover therefore remains in a sort of anteroom to the isolation chamber, between the sidewall 12 and the side partition wall 15, where it is protected from dust and foreign matter. As the carriage continues to be moved inwardly (the condition illustrated in FIG; 4), it of course carries the specimen plate. along with it, until the carriage is stopped when the specimen plate is fully out of its cover and is situated in the isolation chamber between the side partition walls 15 and 16.
When inspection of the specimen plate is completed, the carriage is drawn outwardly by means of the handle 45, and the coverholder, with the cover 33 thereon, moves with the carriage until'it reaches the position in which the whole cover is just outside the sidewall 12, at which point outward movement of the cover and cover holder terminates. The specimen plate, of course, also moves with the carriage. Upon continued outwardmovement of the carriage after the cover holder and cover have reached the position just mentioned, the specimen plate is drawn into the cover, and when the carriage has attained its outermost position, the specimen plate is once again wholly inside the cover and the assembled cover and specimen plate can be lifted flatwise ofi the carriage and out of the cover 1. In combination with a plate having a surface to be exposed when the plate is in a defined exposure zone and which should be protected from exposure at certain other times:
A. a cover for the plate movable parallel to said surface to and from a position covering said surface; 8. a carriage having a portion on which the plate, with the cover thereon, can be supported, said carriage being movable back and forth to carry its said portion between the exposure zone and a defined loading zone, through an intermediate zone;
C. cooperating means on said portion of the carriage and on the plate, operative when the plate is on said portion of the carriage to constrain the plate to move with the carriage; I
D. means connected with the cover providing a first abutment engageable with a fixed part upon movement of the carriage to carry its said portion to the intermediate zone from the loading zone, and by which the cover is restrained against further motion with the carriage that carries the plate to the exposure zone and out of underlying relationship to the cover; and
E. means connected with the cover providing a second abutment engageable with a fixed part upon movement of the carriage that carries its said portion to the intermediate zone from the exposure zone, and by which the cover is restrained against further movement with the carriage that carries the plate back to theloading zone and to underlying relationship with the cover.
2. The combination of claim 1, further characterized by:
A. means defining an isolation chamber in which said exposure zone is situated, said means comprising a wall with an aperture therein through which the carriage is slidable and which provides the fixed part engageable with said first abutment; and
B. means fixed with respect to said wall and spaced from it in the direction that the carriage moves to carry its said portion from the exposure zone to the intermediate zone, the last-mentioned means providing a stop engagcable with said second abutment.
3. In combination with a plate having a surface intended to be exposed only under prescribed conditions, and means defining an isolation chamber in which the plate is intended to be exposed,
means for moving the plate to and from a predetermined situation in said chamber, for protectingthe plate against undesired exposure when it is out of said chamber, and for exposing it when it is in said situation, said last-named means comprising:
A. a cover member lengthwise slidable to and from an assembled relationship with the plate in which the cover member protectively overlies said surface of the plate;
B. a carriage confined to motion in opposite directions along a defined path to carry a portion of the carriage between said situation in the isolation chamber and a loading zone outside the chamber through an intermediate zone, the isolation chamber having an aperture through which said portion of the carriage passes in so moving; C. a holder supported by the carriage for motion relative to the carriage in said directions of carriage motion;
D. means on the holder for detachably securing the cover member thereto to constrain the cover member to move with the holder and by which the cover member is disposed lengthwise parallel to said directions of carriage motion;
E. cooperating means on the plate and on said portion of the carriage for constraining the plate to move with the carriage, the last-mentioned means being engageable upon securement of the cover member to the holder with the plate in assembled relationship to the cover member; and
F. cooperating abutment'means on the holder and on the isolation chamber means for restricting motion of the holder relative to the chamber means and with the carriage said abutment means being arranged l. to confine the holder against movement with said portion of the carriage as the same is moved from the intermediate zone to said situation, to effect exposure of the plate, and
2. to confine the holder against movement with said portion of the carriage as the same is moved from the intermediate to the loading zone, to effect recovering of the plate.
4. The combination of claim 3 further characterized by:
A. the carriage comprising an elongated platelike member having an upper surface which the specimen plate can flatwise overlie and which comprises said portion;
B. the holder having 1. a medial portion which flatwise underlies said platelike member,
2. marginal portions which embracingly slidably engage longitudinal edge portions of the platelike member, and
3. finger portions which project above the platelike member to engage the cover and releasably confine the same against motion relative to the holder.