Video display apparatus

• US 6,657,605 B1
• Filed: 11/01/2000
• Issued: 12/02/2003
• Est. Priority Date: 11/01/2000
• Status: Expired due to Fees

• Current Assignee: Donald E. Hall, JDV Investments, LLC, Jerry Kohl, Whitefish Investments, LLC, W Robert Kohorst Trustee of Everest
• Original Assignee: Donald E. Hall, JDV Investments, LLC, Jerry Kohl, Whitefish Investments, LLC, W Robert Kohorst Trustee of Everest
• Inventors: Deckert, Curt K., Boldt, Norton K. Jr.
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Dharia, Prabodh M.
• Application Number:
  US09/703,916
• Time in Patent Office: 1,126 Days
• Field of Search: 345/39, 345/44, 345/48, 345/64, 345/87, 345/84, 345/89, 348/770, 348/771, 365/106, 353/30, 349/201
• US Class Current: 345/83
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• CPC Class Codes: G09G 2320/0693 Calibration of display systems

Abstract

A color video display apparatus comprises a pixel array with each pixel containing one or more LEDs for generating each of the selected colors and a holographic optical element positioned in front of the array to form the transmitted light into a substantially elliptical pattern. Improved uniformity for the apparatus is achieved by measuring the intensity of each separate color generating LED in each pixel, recording each intensity and varying the current to each separate color LED or LEDs so that every LED or LEDs responsible for each color to provide a suitable color output. A feature of the apparatus is that a number of separate modules, each having a pixel array, can be combined to construct a video image board. These boards have applications in such areas as billboards along roadways and as signs in stadiums.

Claims

1. A video display apparatus for directing light forming a video image In an X, Y, Z coordinate system wherein the X and Y axis form the XY plane that contains the cross section of the dispersed light pattern, and the Z axis is in the direction of the propagation of light and is through the center of the light pattern in the XY plane, comprising:

a. a housing;

b. a plurality of pixels mounted in the housing for generation of pixels of light to make up the video image to be viewed by an observer or observers, each pixel representing the smallest increment of the image, each pixel comprising a plurality of light emitting diodes and each light emitting diode arranged to emit tight outwardly from the housing; and

c. a holographic optical element mounted on the housing in front of each pixel, the holographic optical element being arranged to receive the light emitted by the pixels and disperse the light in a substantially elliptical pattern directly to an observer(s) without using any light emitted modulating guide such that the dispersed light is centered along the Z as ad the pattern is greater along the X axis than along the Y axis.

2. The video display apparatus of claim 1 wherein the housing defines a planar surface, the LEDs being arranged substantially in a plane parallel to the housing surface with the Z axis being perpendicular to the housing surface.

3. The video display apparatus of claim 1 further comprising a mask, the mask securedly fixed to the housing such that the holographic optical element is between the housing and the mask, the mask surrounding the light emission area of each pixel to reduce reflected light.

4. The video display apparatus of claim 1 wherein the housing defines a substantially planer surface and wherein the holographic optical element redirects the light incident from the LEDs such that the redirected light is at an angle which is at least 3 degrees greater than the incident light with respect to the Z axis.

5. The video display apparatus of claim 1 wherein the housing defines a substantially planar surface and further comprising a reflector for each light emitting diode for directing additional light in substantially an outward direction perpendicular to the surface of the housing.

6. The video display apparatus of claim 1 wherein each pixel has at least one light emitting diode for emitting green light, at least one light emitting diode for emitting blue light and at least one light emitting diode for emitting red light.

7. The video display apparatus of claim 1 wherein a plurality of video image modules can be combined to form a video image board.

8. The video display apparatus of claim 1 wherein the holographic optical element can be interchanged with other holographic optical elements providing a variety of forms of transmitted light.

9. The video display apparatus of claim 1 wherein the holographic optical element acts as a diffuser.

10. The video display apparatus of claim 1 wherein the holographic optical element is a surface relief holograph.

17. The video display apparatus of claim 1 wherein the horizontal spread is between about plus 50 degrees and minus 50 degrees and the vertical spread is between about plus 7 degrees to plus 25 degrees and between about minus 7 degrees to minus 25 degrees.

11. A method for characterizing the light output of a video display apparatus having a plurality of pixels, each pixel comprising at least one LED for each color with each pixel representing the smallest increment of the image to be viewed by the observer and a holographic element mounted in front of the pixels to disperse the light in a substantially elliptical pattern directly to an observer(s) without using any light emitted modulating guide comprising:

a. supplying power at a selected level individually to the LED or LEDs for each color in each pixel; and

b. measuring the intensity of the light generated by each LED or LFDs for each color in each pixel.

12. The method of claim 11 further including the step of controlling the power supplied to the LED or LEDs responsible for each color in each pixel to normalize the light output from the display apparatus.

13. The method of claim 11 wherein the step of supplying power to the individual LED or LEDs responsible for each color in each pixel comprises supplying current at a predetermined level for a selected time.

14. The method of claim 13 further including the step of controlling the time that current at said predetermined level is supplied to the LED or LEDs responsive for each color in each pixel to normalize the light out put from the display apparatus.

15. The method for characterizing the output of a video display apparatus by regulating the intensity of each color of claim 11 further comprising the steps of:

a. determining if the intensity of any color specific LED or LEDs in any pixel is below an acceptable level; and

b. removing the video display apparatus and replacing the unacceptable LED or LEDs when any color emitted is below an acceptable level.

16. A video display apparatus, the display to be viewed by one or more observers, comprising:

a. a group of light emitting diodes making up individual pixels, each pixel emitting fight in substantially an outward direction towards the observe(s); and

b. a holographic optical element adapted to receive the light emitted by each pixel and transmitting the light in a substantially elliptical pattern directly to an observer(s) without using any light emitted modulating guide.