Prismatic tracking insolation

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Drawings

FIG. 1 is a perspective view of the tracking insulation 10 prism and withtonoa bisecting with respect dispersion median plane a within the and minimized refraction.

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stated above, the dispersion is by means of a prismatic

PRISMATIC TRACKING INSOLATON solid which refracts bands of light along angularly di vergent "focal lines or planes'. Accordingly, a linear

This is a continuation in part application of applica lens having a focal line or plane is aligned with the tion Ser. No. 30,328, filed Apr. 16, 1979, now aban median focal plane of the selected spectrum portion doned, and is copending with application Ser. No. emitting from the prism to project the same to the target 271,838 filed on even date herewith. collector or converter also of linear form at the point of BACKGROUND focus. In practice, a linear Fresnel lens is used for this projection.

The collection of solar energy for heating and the O Tracking of the sun in its traverse between horizons is generation of power involves the radiation of sunlight either by bodily movement of the apparatus herein dis onto conduits and power generating cells; conduits closed or preferably by turning of the prism disclosed in transporting a heat transfer media and/or energy con a plane substantially normal to the sun in its movement verters that directly produce electrical power. Solar across the sky. In practice, a clock drive more specifi quantity or concentration becomes a primary consider 15 cally referred to as an "astro timer' is employed to ation for the impingement of light rays onto said collec revolve the prism in order to maintain substantial align tor tubes or converters, and heretofore the white light ment of the aforesaid "focal plane' of the prism and lens of the sun rays has been concentrated for so-called high projection respectively. Nominal operational time peri temperature heat collection or conversion. However, it ods are accommodated by revolvement of the prism is known that the longer "red" (infrared) rays of light 20 alone, while extended operational time periods are ac are those which have the greater heating effect, while commodated by combining therewith a reflective mir the shorter "violet" or "ultraviolet' rays have the lesser ror that also moves with the astro timer or clock drive heating effect and are required, for example in photovoltaic powder generation. Furthermore, when to track the selected spectrum onto the target. A feature is the use of an array of prismatic projection units and considering photovoltaic power generation, only high 25 each with its prism and mirror articulated to concen energy photons (some 45% of the solar radiation) will trate the selected spectrum onto the target collector or be effective, ie the ultraviolet and some of the visible converter for high heat and/or power operation. In spectrum, but not the infrared. Also, those invisible infrared rays just beyond the "red" of the visible spec practice ment to therefore, each mirror has its angular adjust the target, and the distance to the target from trum have known penetrating heating effect. Therefore, each prism unit is accommodated by the focal length of it is a general object of this invention to advantageously its projection lens or a collection lens. employ either or both of those rays, namely infrared The optics of the collector prism is critical, with the and ultraviolet at opposite ends of the spectrum, and of apex B uppermost and the quadralateral faces AB and the sun which are known to have said effects, in prefer CB active to refractively pass sunlight so as to disperse ence to those rays that do not; and to this end dispersion the same into the utilitarian spectrum, especially the is employed to break sunlight into its parts which are heat portion thereof. In accordance with this invention then selectively focused upon a target collector or con the lowermost quadralateral face AC is inactive and in verter as circumstances require.

The prism is a solid transparent body that refracts ingly, a feature is the reductionnon-reflective. practice is frosted so as to be Accord of internal reflection light, and strictly speaking is a solid figure with ends of 40 within said prism by maintaining substantial normality equal size and shape in parallel relation and whose sides of the face extending therebetween are parallelograms. The most selection ofAB the to the solar source rays and by careful acute angle at the apex B. Therefore, the common prism is a triangular solid of glass or the like, critical angle of the prism is at the apex B, and the opti for refracting and dispersing light into and beyond the mum of which has been found to be approximately 36 visible spectrum ranging from infrared heat rays to the 45 power generating ultraviolet rays. Dispersion in the based on an air to glass interface and which varies as a prism is by means of refraction or the bending of light function of the respective indicies of refraction, for the rays as they pass obliquely from one medium (air) to the substantial purpose of elimination of internal reflection and for the conducting the tracking function through a other (glass or plastic) or different density in which its speed changes; a phenomenon thereby breaking the 50 wide range, and especially in combination with a mirror light into its constituent parts represented by the bands M that contra rotates there with at a ratio of 1 to 2. That of the spectrum. It is an object therefore to advanta is, the mirror rotation is 1 to 2 of prism rotation. The geously employ said prismatic phenomenon and con relatively small apex angle of the prism operates in centrate therefrom a range of heat rays which is most conjunction with the tracking mirror without the for practical as may be required for application to the target 55 mer blocking light, especially in the heat spectrum por collector or converter. tion, from the latter.

The selection of heat rays involves an alignment with The heat collector and/or power converter can vary that portion of the spectrum both visible and invisible, in form and in construction, however it is disposed and the projection of that portion upon the collector or linearly along the focus of the at least one prismatic-lens converter. The projection of selected heat rays can be collector above referred to. A feature of this invention is the conservation of concentrated heat in the collector direct or concentrated and at a 1 to 1 ratio or at a con centration ratio for developing commensurately high or converter at the point of focus, and which is structur temperature or energy at the target. That is, direct pro ally compact while the collecting prism and tracking jection is suitable for low temperature-low power oper mirror are structurally expansive. In practice, the said ations, while concentrated projection is necessary for 65 collector or converter is encased within a transparent high temperature-high power operations. It is an object tube, preferably vacuumized, for the substantially com therefore to concentrate that portion of the spectrum plete absorption of energy from the heat rays impinging selected for heating and to project it exclusively. As thereupon. A codensing reflector backs up the target to 6 return the heat rays that are or may be dispersed to 1.49 (glass 1.5) and a light transmission factor of 92%; initially pass thereby. said surface coating increasing the said light transmis DRAWINGS sion efficiency. A feature therefore is the lightweight of the plastic, acrylic, prism having a slender cross section

The various objects and features of this invention will 5 and with a specific gravity of 1.19; considerably lighter be fully understood from the following detailed descrip tion of the typical preferred forms and applications in The weight than any glass and much less fragile. prism Preceives parallel solar source rays which thereof, throughout which description reference is enter the normal objective face AB or CB angularly made to the accompanying drawings, in which:

FIG. 1 is a perspective view of the tracking insulation 10 prism and withtonoa bisecting with respect dispersion median plane a within the and minimized refraction.

collector of the present invention, in its preferred form The parallel rays then exit through the angularly related involving an array of prisms and coordinated mirrors. 36' transmission face BC or AB with one stage of sub FIG. 2 is a detailed view showing a modified form of stantial refraction and minimized internal reflection. prismatic tracking collector involving a focusing lens. The prismatic refraction inherently produces spectral FIG. 3 is a diagramatic perspective view illustrating 15 dispersion, with the red and infrared light concentrated the altitude and traverse relationship of the sun to the toward the edge B as the light emits from said prism P. collector.

The light from prism P emanates divergently from

FIGS. 4 through 7 are views similar to FIG. 2 show transmission ing the transition between morning and afternoon oper and in accordance face CB or AB and plays on the target T, with the invention the heat and/or ation, and the reversal of the prism which characterizes 20 energy rays concentrated by prismatic dispersion are the morning and afternoon modes of operation. played upon the target. For example, those rays of the FIG. 8 is a perspective view similar to FIG. 1 and spectrum in the range of yellow, orange, red and unfra shows a second modified form of the present invention, red are played upon the target T for heating and/or wherein the infrared and ultraviolet light is split. energy change as the case by be. Accordingly, a dis And FIG. 9 is a view similar to FIG. 2 showing the 25 persed heat range of light rays from face CB (or AB) is split rays and each involving a focusing lens. played onto the target T, including the infrared rays PREFERRED EMBODIMENT beyond visible range,

Referring now to the drawings, this invention in upon A feature is the geometric focus of heat range rays volves primarily the use of a prism Paligned with its 30 the prismthe target T by use of coordinate revolvement of objective face AB-CB substantially normal to the solar In practice,P aand the mirror M (see FIGS. 4 through 7). first surface reflector mirror is employed, source rays, and disposed to focus heat rays onto a cast of the same acrylic target heat collector or energy converter. It is to be prism and surface coatedplastic as the aforementioned and aluminized for efficient understood that the prism and collector-converter ar relfection. Accordingly, there is a switching means of rangement can be moved bodily, but that it is preferable 35 the astro timer A operating as a clock drive to actuate a to track the sun by revolvement of the prism and by lever means E that revolves the prism P on an axis b maintaining its objective face substantially normal to substantially normal to the altitude of the sun as it tra the sun rays. Accordingly, the collector assembly is verses (see FIG. 3) and so that its objective face AB or immovably disposed substantially normal to the altitude CB remains substantially normal to the sun rays emitted of the sun and with the target T fixed, while the prism in parallel relation. As shown throughout the drawings, Prevolves in timed relation to the traverse of the sun the target T is fixedly positioned as is the axis b of the under control of an astro timer A operating a means D prism P, and the mirror M is positioned by the astro which maintains the focal line at the target. In practice, timer concentration of the heat or energy portion of the spec meansADoperating about said as a clock drive to actuate a lever axis b so that its alignment with trum is desired and accordingly a lens is provided to 45 prism P remains effective to focus said heat range rays focus the heat or energy rays onto the target T. And in upon the target T. As shown, order to track the sun throughout a substantial portion mirror M on an axis c parallel atomeans F revolves the of its traverse across the skies, a mirror M compliments and F are carried by the lever of meansTheaxis b.

means E to move the prism and is coupled to rotate therewith and thereby therewith, as shown. It will be seen that the prism maintain the line of focus upon the target. P-mirror M combination has its projection plane b-c The prism P is an elongate solid of triangular cross and that the mirror M-target T combination has its section having parallel corners A, B and C defining reversely positionable faces AB and CB. The apex angle projection clock drive plane c-d. The astro timer A operates as a also to operate the belt or chain of the

B is critical and its optimum determined to be approxi means F, as shown. Since the target T is fixedly posi mately 36 for glass air interface, while the face AC is 55 tioned, the axis b is the center of rotation of the prism inactive and frosted so as to be nonreflective. It is the P-mirror M combination when adjusting the mirror M purpose of this prism to pass a maximum amount of ligth angularly with respect to the prism P and target T so as and to reduce an/or practically eliminate internal re to bisect the included angle disposed between the said flection, and to these ends the objective face AB or CB projection planes b-c and c-d. Accordingly, the afore is disposed substantially normal to the solar source rays and the critical angle B minimized to 36". The transpar said parallel sun rays are directed toward the target T and divergently dispersed along plane c-d.

ent highly polished faces AB and CB are surface coated The target T is a heat converter or energy generator for maximum light transmission and minimum internal as may be required. Flat plate targets may be employed, reflection. although more sophisticated vacuumized co-cylindrical Structurally, the prism P is made of glass or a plastic 65 collectors or converters are preferred. As shown for material such as "Acuvue 360' as manufactured by example, co-cylindrical tubing is disposed concentric Swedlow, Inc. of Garden Grove, California, a high with an axis d along which it conducts a heat transfer quality cast optical acrylic having a reflection index of media, the inlet of which is in the outer annulus and the 7 heat absorption and outlet of which is from a central means D, E and F actuated thereby, it is the rotative tube on the line d. The target can be an energy con positions of the prism P and mirror M that are coordi verter such as a voltaic power generating means as nated; maintaining the objective face of the prism nor shown in FIGS. 8 and 9 enclosed in a transparent tube mal to the sun rays; and maintaining the reflection of that is vacuumized so that the insolation responsive dispersion light along the plane c-d. A feature is the two elements thereof are centered on the focus line d, in modes of operation for alternately switching of said which case ultraviolet light, shorter wave lengths of the acute apex angle away from the zenith position of the spectrum, are concentrated upon the target. sun; a morning mode as shown in FIGS. 4 and 5, and an Concentration of heat range rays is provided for in afternoon mode as shown in FIGS. 6 and 7. It is to be the lens which receives the dispersed rays from the O observed that the transmission from morning to after prism P or from the mirrior M. As described, the heat noon modes is characterized by a reversal in positioning range rays are projected divergently from the prism P of the prism P and mirror M, always directing light or mirror M, coextensively of the elongated prism and laterally to the fixedly positioned target T at line d. complementary mirror. Accordingly, the lens is coex Accordingly, three distinct movements are involved, tensive with the prism and/or mirror and is positioned s firstly the revolvement of prism Pby means E, secondly on plane b-c or c-d to embrace and collect the heat ray the shifting or reversal in position of the rotational axis spectrum, for example the yellow to infrared rays. As c of prism P and mirror M by means D, and thirdly the shown in FIG. 1, the lens L1 is a first surface reflector revolvement of said mirror M by means F. in the form of an elongated cylindrically concaved The bent angle of the dispersed rays emanating from mirror, cast of the same acrylic plastic as the aforemen the transmitting face of the prism remains the same tioned prism P and mirror M, and surface coated and throughout each mode; compare FIGS. 4 with 5 and 6 aluminized for efficient reflection. Lens L1 is of linear with 7. And to these ends, the transition from morning form that concentrates the divergent spectrum by fo to afternoon mode involves means Dangularly displac cusing it onto the target line at d. Lens L1 is therefore ing the axis c from the median plane a through prism P, centered behind the target and aligned with the plane 25 in each prism mode, so that the bent angle of light is c-d to collect and concentrate insolation onto the target always directed from axis b to axis c. In practice, a T. As shown in FIG. 2, the lens is a Fresnel lens L2 of cradle X is shiftable to have two angularly displaced linear form focusing the divergent spectrum onto the positions with respect to the plane a, one as shown in target line at d. The lens L2 is therefore centered on the FIGS. 4 and 5 and at all rotative prism positions there plane c-d between the turning axis c of mirror M and between, and the other as shown in FIGS. 6 and 7 and the heat concentration line d at the target T. Like the at all rotative positions therebetween. The means F prism, the lens L2 is cast of the same acrylic plastic as revolves the mirror M in response to positions of the prism P, of light weight and optically efficient. In prac lever means E, so that the reflected angle of light from tice, either or both lenses L1 and/or L2 can be simulta the mirror is always directed from c to d. In practice, neously used. 35 the means F is a lever means (as shown) that ensures The above described combinations of elements are that a line drawn normally from the mirror at axis c intended for singular use or multiple use in an array as always bisects plane b-c and plane c-d. Examination of shown in FIG. 1. It is to be understood that solar posi FIGS. 4 through 7 will bear this out, and all of which tion as related to latitude will determine effective angles occurs as the astro timer means A revolves the prism P, of elevation as shown in FIG. 3, and that the seasons 40 there being two mode relationships of prism P and the will cause variations in that angle as well as the effective cradle means X, the one where the prism face AB is the time of day for solar energy collection. Also for exam objective face, and the other one where the prism face ple, it may be that effective insolation can be realized CB is the objective face. There is a switching or rever from one hour after sunrise to one hour before sunset, or sal in position of the prism P, whereby the one prism between shorter or longer hours as determined by loca 45 serves two purposes, or two roles. In both modes the tion at different latitudes. As shown in FIG. 1, the sun incoming light is normal to the objective face of the rays are received by an array of prisms P between prism, and the transmission light is at a bent angle which there is no shadow cast by any one prism upon toward the base AC of the prism. It will be seen from the other. Likewise, the mirror M reflecting the heat FIG. 1 that adjustments are made to the reflective an range portion of the spectrum projects rays one beneath 50 gles of mirros M so as to accomodate the stepped rela the next without obstruction. Concentration is then by tionship of the array as shown.

means of the lens means that focuses on lined along the Referring now to FIGS. 8 and 9 of the drawings and target T. It will be observed that the objective face of to the split ray version of the present invention, this each prism is substantially normal to the parallel incom embodiment employs the features hereinabove de ing light rays, and that the dispersion through the prism 55 scribed with respect to both embodiments of FIGS. 1 P causes divergence of the separated rays. These sepa and 2, as shown in FIGS. 8 and 9. A feature of the rating rays along planes b-care reflected by the mirrors FIGS. 8-9 embodiment is the split mirror M" configura M to project along planes c-d, where they are collected tion and the employment of dual targets T1 and T2, and and focused by lenses L1-L2 upon the target lined. The particularly the target T1 in the form of a voltaic power array is disposed on inclined elevations as shown and generator G that responds to ultraviolet light. The tar the mirrors are tipped thereby so as to be substantially get T2 is in the form of the previously described media normal to the altitude of the sun. The prisms P and conducting heat collector. Accordingly, the ultraviolet mirrors M are driven to move together by coordinate and infrared portions of the spectrum are reflected di means D, E and F motivated by the astro timer A clock vergently by angularly reflective faces 10 and 11 of means, thereby to track the sun and project the re 65 mirror M', the ultraviolet and infrared light being trans flected rays thereof onto said target line d. mitted thereby on separate (second) median planes to Referring now to FIGS. 4 through 7 and to the con the separate targets T1 and T2. It will be observed that trolled articulation by the astro timer A and related the acute apex angle portion of the prism transmits the 8 longer infrared light portion, while the base portion of dispersion from the transmission face of the prism are the prism transmits the shorter ultraviolet portion of the projected by the mirror to said target. sun light, and that the obtusely related reflection faces 3. The concentrating tracking insolation collector as 10 and 11 separate said two portions of the spectrum so set forth in claim 1, wherein the lens means is an elon that they are reflected divergently to the separate tar gated mirror of concaved cross sectional form receiving gets T1 and T2. I will be observed by comparing FIGS. dispersed light from the transmission face of the prism 4 and 6 that switching the acute apex angle of the prism and coextensively focused onto the said target focus causes a reversal of the spectrum cast upon the mirror line.

M or M", between the before and the afternoon modes. 4. The concentrating tracking insolation collector as Therefore, the targets T1 and T2 are also switched (not 10 set forth in claim 1, wherein the lens means is an elon shown) for example as shown in the morning mode of gated refraction lens receiving dispersion light from the FIG. 9 where the target T1 is associated with mirror transmission face of the prism and coextensively fo face 10 and the acute apex angle and the target T2 with cused onto the said target focus line. face 11, it being understood that in the afternoon mode set5.forth The concentrating tracking insolation collector as of FIG. 6 the target T1 is associated with the mirror 15 gated in claim 1, wherein the lens means is an elon Fresnel lens receiving and refracting dispersion face 11 and the target T2 with face 10. In the FIG. 8 light from the transmission face of the prism and coex embodiment the separated spectrum directly plays upon tensively focused onto the said target focus line. the targets T1 and T2 on a one to one basis. In FIG. 9 6. The concentrating tracking insolation collector as the separated spectrum is focused by lenses L3 and LA 20 forth in claim 1, wherein the acute and upon the targets T1 and T2 on a concentration set prism is substantially 36, wherein apex angle of the the mirror is rotat basis. The mirror M', lenses L3 and L4, and the targets ably carried by a cradle means moving with rotation of T1 and T2 are all elongated members ad hereinabove the prism, and wherein the lens means is in a fixed posi described.

Having described only typical preferred forms and 25 tion relative to the target and is an elongated mirror of concaved cross sectional form receiving dispersion light applications of my invention, I do not wish to be limited from the transmission or restricted to the specific details herein set forth, but sively focused onto theface of the prism and coexten said target focus line.

wish to reserve to myself any modifications or varia 7. The concentrating tracking insolation collector as tions that may appear to those skilled in the art as set set forth in claim 1, wherein the acute apex angle of the forth in the limits of the following claims. 30 prism is substantially 36, wherein the mirror is rotat I claim: ably carried by a cradle means moving with rotation of 1. A concentrating tracking insolation collector for the prism, and wherein the lens means is in a fixed posi operation in a plane substantially normal to the altitude tion relative to the target and is an elongated refraction traverse of the sun, and including; lens receiving dispersion light from the transmission an elongated prism of acute apex angle rotatably 35 face of the prism and coextensively focused onto the mounted on a rotational axis disposed in said plane said target focus line.

for tracking the altitude of the sun and for main 8. The concentrating tracking insolation collector as taining said acute apex angle away from the zenith set forth in claim 1, wherein the acute apex angle of the position of the sun, prism is substantially 36, wherein the mirror is rotat the prism being reversible and having divergent faces ably carried by a cradle means moving with rotation of used alternately for the reception and transmission the prism, and wherein the lens means is in a fixed posi of sun rays and dispersion thereof along a first tion relative to the target and is an elongated Fresnel mean plane respectively, lens receiving and refracting dispersion light from the an elongated mirror coextensive with and rotatably 45 transmission face of the prism and coextensively fo mounted on an axis disposed on said first mean cused onto the said target focus line.

plane to reflect the incoming sun rays from the 9. The tracking insolation collector as set forth in any prism and along a second mean plane and to a one of claims 1 through 8, wherein the elongated prism target focus line, refracts ultraviolet light through its acute angle portion an elongated lens means on said second mean plane 50 throughat one side of said first mean plane and infrared light between the mirror and the said target focus line, its base portion at the other side of said first a clock drive means comprising operating means to have mean plane, and wherein the elongated mirror is split to maintain the said reception face of the prism sub ultravilet two angularly related faces, one face receiving stantially normal to the incoming sun rays and the at light from the acute angle portion of the prism transmission of light therefrom along said first 55 the incomingside said one of said first mean plane and reflecting ultraviolet portion of the spectrum along mean plane, operating means to maintain the said a separate second acute apex angle of the prism away from the zenith ing target, and themean plane toward a power generat other face receiving infrared light position of the sun, and operating means to rotat from the base portion of the prism at said other side of ably position the mirror to reflect along said second said first mean plane and reflecting the incoming infra mean plane and onto said target focus line, red portion of the spectrum along a separate second and an elongated insolation responsive target coex mean plane to a heat absorbing target, there being an tensive with said prism and said mirror and dis elongated lens means on each of said separate second posed on the focus line and spaced from and paral mean planes between the angularly related faces of the lel to the axes of prism and mirror rotation. mirror and the power generating and heat absorbing 2. The concentrating tracking insolation collector as 65 targets respectively.

set forth in claim 1, wherein rays toward the infrared t :