EP0062668A1 - Dispositif de filtre optique variable en continu - Google Patents

Dispositif de filtre optique variable en continu

Info

Publication number
EP0062668A1
EP0062668A1 EP19810902925 EP81902925A EP0062668A1 EP 0062668 A1 EP0062668 A1 EP 0062668A1 EP 19810902925 EP19810902925 EP 19810902925 EP 81902925 A EP81902925 A EP 81902925A EP 0062668 A1 EP0062668 A1 EP 0062668A1
Authority
EP
European Patent Office
Prior art keywords
strip
filter device
motion
filter
plane
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19810902925
Other languages
German (de)
English (en)
Inventor
John Klapkiw
Katherine Klapkiw
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0062668A1 publication Critical patent/EP0062668A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B27/00—Photographic printing apparatus
    • G03B27/72—Controlling or varying light intensity, spectral composition, or exposure time in photographic printing apparatus
    • G03B27/73—Controlling exposure by variation of spectral composition, e.g. multicolor printers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/007—Optical devices or arrangements for the control of light using movable or deformable optical elements the movable or deformable optical element controlling the colour, i.e. a spectral characteristic, of the light
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
    • G02B26/023—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light comprising movable attenuating elements, e.g. neutral density filters

Definitions

  • My invention relates generally to optical filters, and more particularly to filters used transmit incident light at a reduced intensity.
  • Certain characteristics of light can be modified by an optical filter. Some filters polarize an incident beam of light, others transmit only certain frequencies of light, and yet others uniformly reduce the intensity of all of the spectral components of an incident beam of light.
  • filters which reduce the intensity of an incident beam are useful for a variety of purposes, such as dimming the light transmitted by the lamp of a photographic enlarger. Some filters can be adjusted to vary the amount of light that they will transmit.
  • variable filters There are numerous types of variable filters known to the prior art.
  • One type includes an elongated strip provided with discrete sections having different optical properties.
  • Another type includes an elongated semi-transparent strip having optical properties which vary continuously along the length of the strip.
  • Each of these types of variable filters have their own advantages and disadvantages.
  • United States patent 3,603,672 of Bestide teaches a device of the first type and includes an elongated film strip extending between two reels.
  • the film strip has sections along its length which have 'different degrees of opacity or different colors'.
  • a pair of his film strip filters are attached in front of the lenses of a pair of sunglasses. Similar devices of the first type are described in United
  • variable filter The second type of variable filter is exemplified by the device described in United States patent 2,120,499 of R. Mackay which includes a plurality of strip filters of different colors and variable opacities. By adjusting the relative positions of the various strip filters different light intensities and colors are produced.
  • variable filter suffers from the disadvantage that the transmitted light cannot be varied continuously, but only in discrete quanta corresponding to the separate filtering sections.
  • the second type of variable filter may be varied continuously, but does not transmit light of a uniform intensity over its entire working surface.
  • I provide a long, semi-transparent strip having a degree of transparence that varies continuously and linearly along its length, and a structure for supporting the strip between a light source and a target surface.
  • the support structure includes a bearing surface around which the strip is trained so as to double back upon itself. Thus, light emitted by the light source radiates through a doubled over portion of the strip.
  • the semi-transparent characteristics of two aligned portions of the doubled over strip combine to produce a uniforn composite transparence.
  • This uniform composite transparence can be varied by adjusting the strip so as to change the aligned portions.
  • inventions of this invention include an elongated strip as described above held in alignment with a fixed filter plate, or a pair of mutually adjustable filter plates.
  • My invention is advantageous in that an optical filter is provided which is both continuously variable and which has a uniform composite transparence along its entire working surface.
  • FIG. 1 is a perspective view of my device being utilized with a photographic enlarger set-up
  • Fig. 2 is a simplified side elevational view of a first embodiment of the filter
  • Fig. 3 is a pictorial representation of the filter used for the purpose of describing the operating principles of this invention
  • Fig. 4 is a simplified side elevational view of a series of colored filters in accordance with this invention
  • Fig. 5 is a simplified sice eleva tional view of a second embodiment of my device having a fixed filter and a movable strip filter.
  • a variable filter constructed in accordance with my invention includes an elongated, flexible, semi-transparent strip 10 having a linearly varying transparence (i.e. optical density) along its length.
  • linearly varying it is meant that the amount of light transmitted through a portion of the filter from a fixed light source is a linear function of the position of that portion on the strip.
  • the filter also includes a support structure 12 having a first closed reel 14, a second closed reel 16, and a number of roller bearings 18, 20, and 22.
  • a first end of the strip is attached to reel 14, intermediate portions of the strip are trained over the roller bearings, and the second end of the strip is attached to reel 16.
  • An adjustment knob 24 is attached to reel 14 and a belt 26 couples the two reels together for mutual rotation.
  • Fig. 1 a photographic enlargement head 28, a light source 30, an exposure table 32 (the target surface), and a piece of photographic print paper 34 supported by table 32.
  • the enlargement head, exposure table, and photographic paper are included in this figure for descriptive purposes and to illustrate a particular use for the present device. It should be apparent throughout this description, however, that the present filter can be used between any light source and target surface.
  • the support structure can be coupled to the enlargement head 28, or, as indicated by broken line 38, the support structure can be attached to table 38.
  • the particular method of attachment is not critical as long as the filter is held between the light source and the optical surface in a stable manner.
  • the strip is trained over the roller bearings so as to form a double thickness. Since the transparence or optical density of the strip varies linearly along its length, the composite transparence of the double thickness of the strip has a uniform transparence along the aligned length. This composite transparence can be varied by aligning different portions of the strip. In the present embodiment this is accomplished by rotating knob 24 in a clockwise or counter clockwise direction.
  • Fig. 2 an alternate construction for the support structure is shown to include an elongated, transparent or semi-transparent plate 42 disposed between the doubled over strip 10'. Again, the rotation of the reels 14' and 16' adjusts the degree of composite transparence of the filter.
  • the alternate embodiment of Fig. 2 is advantageous in that it can be made thin enough to fit within the filter slot of the enlargement head.
  • the plate 42 may be tinted to provide a continuously variable colored filter.
  • a doubled over filter strip 46 is placed between a light source 44 (in this case an incandescent light bulb) and a target surface 48 (here shown as an eye).
  • a light source 44 in this case an incandescent light bulb
  • a target surface 48 here shown as an eye
  • a series of points along the strip have been numbered to indicate the relative transparence of the strip at that point.
  • the optical density at point 5 is 2-1/2 times the optical density at point 2, and allows only 2/5 the amount of light to be transmitted therethrough.
  • the amount of light reaching target surface 48 from the light source is the same as if a fixed sheet filter of relative value 8 were placed therebetween. If the strip were re-adjusted so that point 1 was in alignment with point 6 the filter would be optically identical to a fixed sheet filter of relative value 7.
  • variable density filters 50, 52, and 54 are disposed between a light source 56 and a target surface 58. These filters are tinted the primary colors as indicated and linearly vary in transparence as described above. An assembly such as this is useful in the production of color prints.
  • FIG. 5 an alternate embodiment of this invention is shown to include a movable first strip 60 having a linearly varying transparence, and a fixed second strip or plate 62 having a linearly varying transparence which varies as the inversely with respect of strip 60.
  • the two strips are held in alignment between a light source 64 and an optical surface 66 .
  • the composite transparence of the filter can be varied by moving strip 60 back and forth with strip 62 held immobile.
  • strip 62 could also be moved to vary the composite translucence of the filter.
  • Another embodiment of the present invention includes an endless loop filter having the above described linearly varying transparence and having a doubled portion as described above. Yet another embodiment includes an associated pair of filter strips or plates each having linearly varying transparencies. It is intended that the appended claims include all such embodiments of this filter as fall within the true spirit and scope of this invention.

Landscapes

  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Astronomy & Astrophysics (AREA)
  • Optical Filters (AREA)

Abstract

Filtre pouvant etre regle pour transmettre des quantites variables de lumiere, et caracterise par un degre uniforme de transparence sur toute sa partie de travail. Un mode de realisation de ce filtre comprend une bande (10) allongee, flexible et semi-transparente possedant un degre de transparence variable de facon lineaire, une paire de bobines (14 et 16) autour desquelles sont enroulees les extremites de la bande, et trois paliers a rouleau (18, 20, 22) servant a soutenir la bande pliee en deux entre une source de lumiere (30) et une surface de cible (32). Un bouton (24) de reglage sert a aligner les differentes portions de la bande pliee en double et permet ainsi de faire varier le degre de transparence composite du filtre.
EP19810902925 1980-10-20 1981-10-16 Dispositif de filtre optique variable en continu Withdrawn EP0062668A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US19905080A 1980-10-20 1980-10-20
US199050 1980-10-20

Publications (1)

Publication Number Publication Date
EP0062668A1 true EP0062668A1 (fr) 1982-10-20

Family

ID=22735999

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810902925 Withdrawn EP0062668A1 (fr) 1980-10-20 1981-10-16 Dispositif de filtre optique variable en continu

Country Status (2)

Country Link
EP (1) EP0062668A1 (fr)
WO (1) WO1982001423A1 (fr)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2734435A (en) * 1956-02-14 Filter
DE936843C (de) * 1953-02-21 1955-12-22 David Samuel Cronsioe Verfahren und Vorrichtung zur Abpassung der Farbtiefe bei photographischen Farbfiltern
GB1214108A (en) * 1968-04-29 1970-12-02 Paul Bastide Device for controlling amount of light passing through or reflected by optical apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8201423A1 *

Also Published As

Publication number Publication date
WO1982001423A1 (fr) 1982-04-29

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Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): FR

STAA Information on the status of an ep patent application or granted ep patent

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18D Application deemed to be withdrawn

Effective date: 19821220