Light chopper assembly

• US 4,909,600 A
• Filed: 10/28/1988
• Issued: 03/20/1990
• Est. Priority Date: 10/28/1988
• Status: Expired due to Term

• Current Assignee: GE Inspection Technologies LP (General Electric Company)
• Original Assignee: Welch Allyn Incorporated
• Inventors: Danna, Dominick A., Ciarlei, Joseph A., Rink, Gary L.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): Ben, Loha
• Application Number:
  US07/264,258
• Time in Patent Office: 508 Days
• Field of Search: 350/314, 350/317, 350/318, 350/316, 350/315, 350/311, 350/273, 350/274, 358/42, 358/98, 358/103, 356/320, 356/233, 250/233
• US Class Current: 359/235
• CPC Class Codes: G02B 26/008 in the form of devices for effecting sequential colour changes, e.g. colour wheels
• CPC Class Codes: G02B 26/04 by periodically varying the intensity of light, e.g. using choppers shutters, diaphragms for cameras G03B9/00; devices for eliminating or reducing the effect of flicker in projection systems G03B21/40
• CPC Class Codes: G02B 7/006 Filter holders
• CPC Class Codes: G21K 1/04 using variable diaphragms, shutters, choppers
• CPC Class Codes: G21K 1/043 changing time structure of beams by mechanical means, e.g. choppers, spinning filter wheels

Abstract

A light chopper wheel for use in a video system that is capable of producing either black and white or full color images. The wheel is formed of two circular sheet metal plates that are joined in back-to-back contact. A first series of circumferentially spaced color filter windows are located about a first diameter on the wheel and a second series of clear windows are circumferentially spaced about a second diameter on the wheel so that a clear window is radially adjacent each color filter window. Recesses are stamped in the back of each plate behind each color filter window and filters are mounted between the plates within the recesses.

Claims

1. A light chopper assembly that includes

a wheel that is arranged to pass through a fixed light beam and which is formed by joining a pair of similarly shaped thin metal plates in back-to-back contact,

said wheel having a series of filter windows circumferentially spaced about a first diameter on the wheel and a second series of clear windows circumferentially spaced about a second diameter on the wheel,

a color filter means mounted between the plates behind each filter window,

each color filter means being transparent to said light beam to permit light to pass therethrough, and

each filter window being positioned adjacent to a clear window so that two opposed side walls of the adjacent windows lie along a common radius of said wheel whereby each window is capable of passing through the light beam in the same period of time.

2. The assembly of claim 1 that further includes hub means for connecting the wheel to a drive means.

3. The assembly of claim 1 wherein said filter windows are spaced at equal intervals about said first diameter and the clear windows are spaced adjacent to the filter windows, at the same intervals about said second diameter.

4. The assembly of claim 3 wherein the wheel contains three filter windows spaced at 120 degree intervals and further includes a red filter, a green filter and a blue filter.

5. The assembly of claim 1 wherein each plate contains a deformable tab means that are bent over and clamped against the other plate in assembly.

6. The assembly of claim 1 that further includes a recess that is stamped into the back of each plate about the perimeter of each filter window in which a filter is mounted.

7. A light chopper assembly for use in a video system for creating either black and white images, or full color images of a target, said light chopper assembly including

a pair of complementary circular sheet metal plates each having a flat back surface and a flat front surface,

each plate having a plurality of cutouts formed therein, each cutout further including a pair of opposed radially disposed side walls that pass inwardly from outer peripheral wall of the plate toward the center of the plate, a bottom wall extending between the two radially disposed side walls and a rib that extends between the side walls to divide the cutout into an upper aperture and a lower aperture,

each plate being deformed outwardly from its back surface toward its front surface to form a recess about the perimeter of each lower aperture,

means to join said plates in back-to-back contact so that the apertures are in co-aligned registration with each other whereby the recessed lower apertures form a series of filter windows that are circumferentially spaced about a first diameter and the upper apertures form a series of clear windows that are circumferentially spaced about a second diameter, and

a color filter mounted between the plates within each recessed filter window.

8. The light chopper assembly of claim 7 wherein each rib includes a deformable tab depending outwardly from the outer rim thereof, said tab being bent over an adjacent rib in assembly to secure the plates in back-to-back contact.

9. The light chopper assembly of claim 8 that further includes a centrally mounted hub means for coupling the assembly to a drive means.

10. The light chopper assembly of claim 9 having three filter windows and further includes a red, a green and a blue filter mounted in respective windows so that the filter moves in sequence past a fixed point as the assembly is rotated about the hub means.