METHOD AND APPARATUS FOR MEASURING THE CRITICAL FLICKER FUSION FREQUENCY

• US 3,814,510 A
• Filed: 02/25/1972
• Issued: 06/04/1974
• Est. Priority Date: 03/05/1971
• Status: Expired due to Term

• Current Assignee: Georges Ducommun, Karl Adler
• Original Assignee: Georges Ducommun, Karl Adler
• Inventors: Adler, Karl, Ducommun, Georges
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Sacher, Paul A.
• Application Number:
  US05/229,492
• Time in Patent Office: 830 Days
• Field of Search: 351/36,39
• US Class Current: 351/243
• CPC Class Codes: A61B 5/161 Flicker fusion testing eye testing A61B3/00
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators

Abstract

A method and apparatus for measuring the critical flicker fusion frequency of a person, wherein flickering light pulses are displayed for observation on an area surrounded by a ring-shaped area illuminated by an adaptation light appearing as a constant non-flickering light.

Claims

1. A method for measuring the critical flicker fusion frequency of a person, comprising producing light pulses of variable frequency and displaying them to a person to be tested by means of a flickering illumination appearing in the center of a display screen, and producing and displaying simultaneously a ring of continuous adaptation illumination round said flickering light, on the same display screen, said flickering illumination and said adaptation illumination being displayed separately from each other but without visible boundary zone between them.

2. An apparatus for measuring the critical flicker fusion frequency of a person, comprising a circular plane display screen, a flickering light source energized by an electronic variable-frequency pulse generator and disposed for display in a central portion of said screen in order to produce a flickering illumination, and an adaptation light source surrounding said flickering light source and energized for producing a continuous adaptation illumination, said adaptation light source disposed for display in a peripheral portion of said screen, wherein said adaptation light source surrounds said flickering light source without interference and without any visible boundary zone therebetween.

3. An apparatus according to claim 2, comprising means for varying the intensity of the adaptation light source.

4. An apparatus according to claim 2, comprising a flickering light source of low inertia and a rectangular-pulse generator for energizing said flickering light source.

5. An apparatus according to claim 4, wherein said pulse generator includes a means allowing adjustment of a variable ratio between the duration of pulses and pulse intervals respectively.

6. An apparatus according to claim 4, wherein said pulse former includes logical means for preselection of all ratios between entire numbers beTween 1:

99 and 99;

1.

7. An apparatus according to claim 2, comprising means for preselection of the pulse amplitude.

8. An apparatus according to claim 2, having a rotatable adjusting member for the generator frequency, and comprising a disengageable locking mechanism allowing rotation of said adjusting member in the sense of decreasing frequencies only if said locking mechanism is engaged.

9. An apparatus for measuring the critical flicker fusion frequency of a person, comprising a flickering light source energized by a variable-frequency pulse generator in order to produce a flickering illumination, and an adaptation light source surrounding said flickering light source and energized for producing a continuous adaptation illumination, said flickering illumination and said continuous adaptation illumination being accommodated in a common illumination unit having a cylindrical casing including a back and an opal disc at its front side, a space enclosed within said casing between said back and opal disc being subdivided by a thin opaque partition wall extending from said back to said disc into concentric compartments, a flash illumination of said flickering light source being located in the inner of said compartments while means for continuous illumination are located in the outer annular compartment.

10. An apparatus according to claim 9, wherein said flash illumination is a spiral-shaped flash tube.

11. An apparatus according to claim 9, wherein said means for continuous illumination comprise a ring of incandescent lamps.

12. An apparatus for measuring the critical flicker fusion frequency of a person, comprising a flickering light source energized by an electronic variable-frequency pulse generator in order to produce a flickering illumination, and an adaptation light source surrounding said flickering light source and energized for producing a continuous adaptation illumination, said flickering illumination and said continuous adaptation illumination being accommodated in a common illumination unit having a casing including an opal disc at its front side, a space enclosed within said casing inside said opal disc, this space being subdivided into concentric compartments by opaque partition means extending from said disc, said flickering light source being located in the inner of said compartments and said means for continuous adaptation illumination being located in the outer annular compartment.