ILLUMINATION SYSTEM FOR COLOR ENLARGERS AND THE LIKE

• US 3,756,712 A
• Filed: 12/14/1971
• Issued: 09/04/1973
• Est. Priority Date: 12/14/1971
• Status: Expired due to Term

• Current Assignee: Louis L. Weisglass, Robert A. Flieder
• Original Assignee: Louis L. Weisglass, Robert A. Flieder
• Inventors: Weisglass, Louis L., Flieder, Robert A.
• Primary Examiner(s): Matthews, Samuel S.
• Assistant Examiner(s): Gellner, Michael L.
• Application Number:
  US05/207,992
• Time in Patent Office: 630 Days
• Field of Search: 355/32,35,71
• US Class Current: 355/71
• CPC Class Codes: G03B 27/73 Controlling exposure by variation of spectral composition, e.g. multicolor printers

Abstract

In the apparatus disclosed, three dichroic filters partially intercept a white light beam emerging from a light source having an elliptical reflector with a focal point at the location of the filters. The filters thus divide the beam into a white portion and an intensely colored portion. The beam enters a mixing chamber through a porthole and strikes a slanted white-opaque ceiling to form a hyperbolic section. White-opaque sidewalls coact with the ceiling to mix the white and intensely colored light. The light exists through a diffuser at the bottom of the chamber so that it can be used to illuminate a color negative in a color enlarger which focuses the light on printing paper. A cylindrical mirror at the entrance porthole reflects a part of the marginal portion of the colored part of the beam toward the white side while reflecting part of the white light into the intensely colored light. This allows the mixing chamber to blend the light and avoid a color wedging effect on the print. The diffuser at the exit of the chamber tapers from a thick center outwardly toward thinner edges. Thus, the diffuser scatters more of the light at its center and transmits more at its edges. This compensates for falloff of intensity from center to outside. The scattering of light within the diffuser causes unused light to reenter the chamber for further mixing. A matte finish on the bottom of the diffuser prevents the light which is reflected by a carrier holding the film from being rereflected onto the edges of the film.

Claims

1. An illuminating system, comprising source means forming a light beam, filter means in the path of only a portion of the beam for coloring a portion of the beam, mixing chamber means having an opening in the path of the beam beyond said filter means and having opaque reflective dispersing means for mixing the light of the beam entering said chamber means, said chamber means having an exit window for allowing egress of the light from said chamber means, a transparent diffusing plate covering the window for diffusing light as it leaves said chamber means, said filter means being movable across the beam, said source means focusing the beam so as to produce a focus between said source means and the opening of said chamber means.

2. A system as in claim 1, wherein said filter means is located so as to be movable across the beam at the focus.

3. A system as in claim 1, wherein the beam converges and then diverges before reaching said chamber means, said chamber means including mirror means extending substantially parallel to the axis of the beam but intersecting the beam at the opening for mingling the portion of the beam passing through the filter means with the portion of the beam which passes the filter means, said mirror means having a reflecting surface for reflecting light on one side of the beam to the other.

4. An enlarger comprising a housing, light source means in said housing for forming a light beam, filter means in said housing in the path of a portion of the beam for coloring a portion of the beam, mixing chamber means in the housing and having an opening in the path of the beam and opaque dispersing means for mixing the light of the beam entering the chamber means, said filter means being located along the beam between said chamber means and said source means, said chamber means having an exit window for allowing exit of light from said chamber means, a translucent diffusing plate covering the window for diffusing light as it leaves said chamber means, optical means for focusing light emerging from said diffusing plate, and printing paper holding means for holding printing paper near the focus of said optical means, said source means focusing the beam and forming a focus between said source means and said mixing chamber means, the focus being closer to said filter means than said mixing chamber means.

5. An enlarger as in claim 4, wherein said filter means is movable across said beam, said filter means being movable through the focus.

6. An enlarger comprising a housing, light source means in said housing for forming a light beam, filter means in said housing and in the path of a portion of the beam for coloring a portion of the beam, mixing chamber means in said housing and having an opening in the path of the beam and opaque dispersing means for mixing the light of the beam entering the chamber means, said chamber means having an exit window for allowing exit of light from said chamber means, a translucent diffusing plate covering the window for diffusing light as it leaves the chamber means, optical means for focusing light emerging from said diffusing plate, and printing paper holding means for holding printing paper near the focus of said optical means, said diffusion plate including a diffusion material distributed so as to achieve greater diffusion power toward the center than the outer portion thereof.

7. An enlarger, as in claim 6, wherein said chamber means includes mirror means extending substantially parallel to the beam but intersecting the beam at the opening of said chamber means and having reflecting surfaces for reflecting the light on one side of the beam to the other side within the chamber means.

8. An enlarger, as in claim 6, wherein said translucent diffusing plate has a given thickness at the center and become progressively thinner toward the edges, said plate being composed of material having a diffusion power varying with the thickness of the plate.

9. An enlarger, as in claim 6, wherein said diffusing plate has an outer face and an inner face relative to said chamber means, said outer face having a matte finish.

10. An illuminating system, comprising source means forming a light beam, filter means in the path of only a portion of the beam for coloring a portion of the beam, mixing chamber means having an opening in the path of the beam and opaque reflective dispersing means for mixing the light of the beam entering said chamber means, said chamber means having an exit window for allowing egress of the light from said chamber means, a transparent diffusing plate covering the window for diffusing light as it leaves said chamber means, said chamber means including mingling means in the path of the beam for mingling the portion of the beam passing through the filter means with the beam portion which passes by the filter means, said mingling means having mirror means extending substantially parallel to the beam but intersecting the beam at the opening and having a reflecting surface for reflecting light on one side of the beam to the other.

11. A system, as in claim 10, wherein said mirror means includes a cylindrical mirror having an axis extending substantially along the axis of the beam and having an interior reflEcting surface.

12. A system, as in claim 11, wherein said dispersion plate includes a diffusing material distributed so as to achieve a greater diffusion toward the center than the outer portion thereof.

13. A system, as in claim 11, wherein the translucent diffusing plate has a given thickness at the center and becomes progressively thinner toward the edges, said diffusing plate being composed of a material having a diffusion power which varies with the thickness of the material.

14. A system, as in claim 11, wherein said diffusing plate has an outer surface relative to the chamber and an inward surface relative to the chamber, said outer surface having a matte finish.

15. A system, as in claim 10, wherein said mirror means includes two mirror surfaces on opposite sides of the beam for reflecting light on opposite sides of the beam toward each other.

16. A system, as in claim 10, wherein the mirror surface extends along two flat planes intersecting the beam.

17. A system, as in claim 16, wherein said plate has a frusto-conical shape thicker in the center and decreasingly thick towards the edge, said plate being made of a material having a diffusion power which increases with the thickness of the plate.

18. A system, as in claim 16, wherein said plate includes a diffusing material distributed so as to achieve a greater diffusion towards the center than the outer portion thereof.

19. A system, as in claim 16, wherein said diffusing plate has a surface facing inwardly relative to the chamber means and a surface facing outwardly relative to the chamber means, said outwardly facing surface having a matte finish.

20. A system, as in claim 16, wherein said source means includes reflector means for producing a converging and then diverging beam, said mirror means being in the diverging portion of the beam.

21. A system, as in claim 10, wherein said source means include reflector means for producing a converging and then diverging beam.

22. A system, as in claim 21, wherein said chamber means include mirror means extending substantially parallel to the beam but intersecting portions of the beam at the opening of said chamber means and having a reflecting surface for reflecting light on one side of the beam to the other side, said mirror means being located in the diverging portion of the beam so as to intersect the beam.

23. A system, in as in claim 10, wherein the translucent diffusing plate has a given thickness at the center and becomes progressively thinner toward the edges, said diffusing plate having a diffusion power varying with the thickness of the plate.

24. A system, as in claim 10, wherein said diffusing plate includes diffusing material distributed to achieve a greater diffusion power toward the center than at the outer portions thereof.

25. A system, as in claim 10, wherein said diffusing plate has an outwardly facing surface and an inwardly facing surface relative to said chamber means, said outwardly facing surface having a matte finish.

26. A system, as in claim 25, wherein said mirror means is in the diverging portion of the beam.

27. A system as in claim 10, wherein said filter means is located between said source means and said chamber means, said source means forming a focus between said source means and said chamber means.

28. A system as in claim 27, wherein said filter means are movable transverse to the beam through the focus.

29. An illuminating system, comprising source means for forming a light beam, filter means in the path of a portion of the beam for coloring a portion of the beam, mixing chamber means having an opening in the path of the beam and opaque reflective dispersing means for mixing the light of the beam entering said chamber means, said chamber means having an exit window for allowing egress of the light from said chamber means, a transparent diffusing plate covering the window for diffusing light as it leaves said chamber means, said diffusing plate including a diffusing material distriButed so as to achieve greater diffusion power toward the center than the outer portion thereof.

30. A system, as in claim 29, wherein said translucent diffusing plate has a given thickness at the center and becomes progressively thinner towards the edges.

31. A system, as in claim 30, wherein said plate has a portion having a frusto-conical shape thicker in the center and decreasingly thick toward the edges.

32. A system, as in claim 30, wherein said plate includes a surface facing outwardly of said chamber means and a surface facing inwardly of said chamber means, said outwardly facing surface being flat and said inwardly facing surface having a central mesa with conically declining walls.

33. A system, as in claim 29, wherein said plate has a portion having a frusto-conical shape thicker in the center and decreasing toward the edges, said plate being composed of a material having diffusion power varying with the thickness of the material.

34. A system as in claim 29, wherein said filter means is located between said source means and said chamber means, said source means forming a focus between said source means and said chamber means.

35. A system as in claim 34, wherein said filter means are movable transverse to the beam through the focus.

36. An illuminating system, comprising source means for forming a light beam, filter means in the path of a portion of the beam for coloring a portion of the beam, mixing chamber means having an opening in the path of the beam and opaque reflective dispersing means for mixing the light of the beam entering said chamber means, said chamber means having an exit window for allowing egress of the light from said chamber means, a transparent diffusing plate covering the window for diffusing light as it leaves said chamber means, said diffusing plate having a surface facing outwardly of said chamber means and a surface facing inwardly of said chamber means, said outwardly facing surface having a matte finish.

37. A system, as in claim 36, wherein said outwardly facing surface is flat.

38. A system, as in claim 36, wherein said plate has portion having a frusto-conical shape thicker in the center and decreasingly thick toward the edge, said plate being composed of a material having a diffusion power that varies with the thickness of the material.

39. A system, as in claim 36, wherein said diffusing plate includes a diffusing material distributed so as to achieve a greater diffusion power towards the center than the outer portions thereof.

40. A system, as in claim 36, wherein said source means includes reflector means for producing a converging and then diverging beam, said chamber means including mingling means in the path of the beam for mingling the portion of the beam passing through the filter means with the beam portion which passes by the filter means, said mingling means having mirror means extending substantially parallel to the beam but intersecting the beam at the opening and having a reflecting surface for reflecting light on one side of the beam to the other, said mirror means being located in the diverging portion of the beam.

41. A system, as in claim 36, wherein the translucent diffusing plate has a given thickness at the center and becomes progressively thinner toward the edges, said diffusing plate having a diffusion power varying with the thickness of the plate.

42. A system, as in claim 36, wherein said diffusing plate includes diffusing material distributed to achieve a greater diffusion power toward the center than at the outer portions thereof.

43. A system, as in claim 36, wherein said chamber means includes mingling means in the path of the beam for mingling the portion of the beam passing through the filter means with the beam portion which passes by the filter means, said mingling means having mirror means extending substantially parallel to the beam but intersecting the beam at the opening and having a reflecting surface for reflecting light on one side of the beam to the Other, said mirror means is in the diverging portion of the beam.

44. A system, as in claim 36, wherein the translucent diffusing plate has a given thickness at the center and becomes progressively thinner toward the edges, said diffusing plate being composed of a material having a diffusion power which varies with the thickness of the material.

45. A system, as in claim 36, wherein said diffusing plate includes a diffusing material distributed so as to achieve a greater diffusion power towards the center than the outer portions thereof.

46. A system as in claim 36, wherein said filter means is located between said source means and said chamber means, said source means forming a focus between said source means and said chamber means.

47. A system as in claim 46, wherein said filter means is located between said source means and said chamber means, said source means forming a focus between said source means and said chamber means.