JPH03143428A - Apparatus for measuring flicker frequency - Google Patents

Abstract

PURPOSE:To enable a CFF value of high reliability and stability to be measured by measuring under a condition of avoiding a motion of head, reducing influences of measuring environment and setting a focal length to that of a subject. CONSTITUTION:The subject confirms whether an inside of eyepiece part 13 can be observed with both eyes while putting the forehead onto the eyepiece part 13. If a focal length does not match the subject, a focal length change part 17 will be adjusted. The subject looks at a mark while fixing the head to the head rest part 16. The subject observes a flashing light 121, discriminates whether it is felt to be a flickering or continuous light and inputs a result of discrimination into a flicker discrimination input part 15. A signal 151 for changing a rotation number of light shutter part 12 is sent to a shutter rotation control part 14. A part of disk, which is made of paper or wood, formed into a sector and fully painted, is utilized as the light shutter part 12. A motor, whose number of rotation is made changeable by an electric signal, is utilized as the shutter rotation control part 14.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention makes it possible to measure CFF values with high reliability by removing the influence of background light and position of optotypes on critical flicker frequency (CFF). The present invention relates to a flicker frequency measuring device.

(Conventional technology) In recent years, VDT (VDT is Visual Vispla
yTer...1nal, Visual Display Terminal, Visual Display Terminal) With the increase in work, an increasing number of workers are complaining of eye fatigue. It is necessary to measure the symptoms and take appropriate measures according to the symptoms. As a device for investigating the function of the human eye, the critical flicker frequency, so-called OFF (CFF), is
ical FlickerFreQuenC1/, critical flicker frequency, is an abbreviation for critical flicker frequency)6 When the eyes become tired, the sensitivity to flicker frequency becomes dull, and CFF
It is known that the value decreases.

As a conventional CFF measuring device, for example, there is a sector type flicker described in the book "How to look at biological functions - Application to ergonomics-j" (co-authored by Kunie Hashimoto and Toshio Endo, published by Ningen to Gijutsusha), page 104. A device called a chain side gauge is known.

FIG. 4 shows a basic ellipse diagram of this device. This device is
This is a device that obtains blinking light 121 by blocking light 111 from an optotype light source section 11 with a light blocking section 12 and rotating the light blocking section 12 with a blocking section rotation control section 14. The subject observes the blinking light 121 through the eyepiece 43, judges whether the blinking light 121 feels like flickering or continuous light, and inputs the judgment result to the flicker judgment input section 15.

However, in this device, the close contact between the eyepiece 43 and the surface of the human face is poor, and surrounding light enters through the gap.
navia (Acta Physiology Scandinavia), 1952, Vol. 30, pp. 161-170, C.
, Mr. Berger created the r l1lunation o
fsurrounding field and fl
As described in a paper titled ``Illuminated Field and Flicker Fusion Frequency'', C.
Since the FF changes depending on the background brightness, the CFF value may change if the CFF measurement environment changes. Furthermore, since the subject's head is not fixed in this device, if the subject's head moves, the position of the flashing light within the visual field, that is, the retinal position changes. Journal of GeneraPs
psychology (Journal of General
Psychology), 1933, Volume 15, 161-17
R, T, Ross on page 0 rThe fusion
frequency different are
as of the visual field: 11
゜TM regional gradient of
As described in a paper entitled "The Fusion Frequency: Indifferent Airs of the Visual Field: The Regional Gradient End of Frequency," the CFF changes depending on the retinal position of the flashing light. If the head moves during measurement, the CFF value may change.

In addition, the Rerry-Porter law and Granlt
As known from the Harper e7) law, C
FF also changes depending on the brightness and size of the flashing light. However, in a top-mounted device, the viewing distance to the flashing light is constant for all subjects, so the CFF value may change depending on the focal length of the subject.

(Problems to be Solved by the Invention) In the conventional OFF device described above, the background brightness easily changes depending on the measurement environment, the subject's head moves easily, and the viewing distance to the flashing light is constant, so the CFF The reliability of the value measurement could not be made sufficiently high.

An object of the present invention is to provide a flicker frequency measuring device that can measure CFF values with high reliability.

(Means for Solving the Problems) Means provided by the present invention to solve the above-mentioned problems is a flicker frequency measuring device that measures critical flicker frequency as one element that quantitatively represents human visual function. a head fixing means for fixing a human head; an optotype light source that emits continuous light; and generating blinking light by intermittently blocking the continuous light emitted from the optotype light source. a light blocking means for controlling the frequency at which the light blocking means blocks the continuous light; and a judgment for determining whether the blinking light feels like flickering or continuous light to the human. and flicker judgment input means for inputting.

(Function) The present invention includes head fixing means for fixing the subject's head. By doing so, it is possible to eliminate fluctuations in the CFF value due to movements of the subject's head.

Furthermore, the present invention includes an eyepiece means that closely fits the surface shape of a human face and can change the viewing distance up to blinking according to the will of the subject or experimenter. By doing so, it is possible to remove the influence of the surroundings of the subject's eyes and to measure a CFF value adapted to the focal length of the subject.

(Example) Next, an example of the present invention will be described with reference to the drawings.

The basic configuration diagram of one embodiment of the CFF measurement device of the present invention is shown in the first example.
As shown in the figure.

Before measuring OFF, place the subject's forehead on the eyepiece 13 and check whether the inside of the eyepiece 13 can be observed with both eyes. At this time, if the subject's focal length does not match, the focal length variable section 17 is adjusted. In this embodiment, the focal length variable portions 17 are provided at two locations, but it is also possible to provide only one of them. Furthermore, it is also possible to fix the subject's head using the head fixing section 16 and clearly see the optotype.

Light 111 from the optotype light source section 11 is blocked by the light blocking section 12,
This is a device that obtains blinking light 121 by rotating the light blocking section 12 using the blocking section rotation control section 14. The subject observes the flashing light 121 (through the eyepiece 13), judges whether the flashing light 121 feels like flickering or continuous light, and inputs the judgment result into the flickering judgment input section 15. Enter. The flicker judgment input section 15 sends a signal 151 for changing the rotation speed of the light blocking section 12 to the blocking section rotation control section 14 based on the test subject's judgment result.

As the eyepiece part 13, for example, a rubber having a shape that can be brought into close contact with the unevenness of a human's forehead, the hollows of the eyes, and the protruding part of the nose as shown in FIG. 2(a) can be used. Also,
As the variable focal length section 17, a cylinder having a variable length as shown in FIG. 2(b) can be attached to the eyepiece section 13 and used.

Furthermore, focus 1? [[As the variable section 17, an optical system using a lens can be inserted between the eyepiece section 13 and the light blocking section 12 or between the light blocking section 12 and the optotype light source section 11.

As the head fixing part 16, for example, a commercially available condylar table (face fixing device) as shown in FIG. 3(a) or a third
A head fixation band as shown in the figure can be used.

As the light blocking portion 12, it is possible to use, for example, a disk made of paper or wood with a portion filled in a fan shape. In addition, as the blocking unit rotation control unit 14, for example,
It is possible to use a motor whose rotation speed can be varied using an electrical signal.

As the flicker judgment input section 15, for example, a push button switch can be used.

(Effects of the invention) By using the present invention, it is possible to avoid head movement, reduce the influence of the measurement environment, and measure according to the subject's focal length, resulting in high reliability. , there is an effect that a stable CFF value can be measured.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram illustrating the eyepiece section in FIG. 1, and FIG. 3 is a diagram illustrating the head fixing section in FIG. 1. , Figure 4 shows the OFF state according to the prior art.
FIG. 2 is a basic configuration diagram of a measuring device. 11... Optotype light source section, 111... Light, 12...
Light blocking unit, 121... Flashing light, 14... Blocking unit rotation control unit, 13... Eyepiece unit, 15... Flicker judgment input unit, 16... Head fixing unit, 17... - Focal length variable section, 43... eyepiece section. 17, :,, :, Distance trick Figure (a) (1)) Figure 2 (b) Figure 4

Claims (4)

[Claims] (1) A device for measuring critical flicker frequency as one element that quantitatively represents human visual function, comprising: a head fixing means for fixing the human head; and an optotype light source that emits continuous light; a light blocking means for intermittently blocking the continuous light emitted from the optotype light source to generate blinking light; a blocking frequency control means for controlling the frequency at which the light blocking means blocks the continuous light; A flicker frequency measuring device comprising: a flicker judgment input means for inputting a judgment as to whether the blinking light feels like flickering or continuous light to the human. (2) By injecting a flashing light into a human's eyes and determining whether or not that person perceives the flashing light as flickering light,
In a device that measures critical flicker frequency as one element that quantitatively represents human visual function, light other than the blinking light enters the human eye when it comes into contact with the face around the human eye. an eyepiece means for blocking the optotype, an optotype light source that emits continuous light, a light blocking means that intermittently blocks the continuous light emitted from the optotype light source to generate the blinking light; a cutoff frequency control means for controlling the frequency at which the cutoff means cuts off the continuous light; and a flicker judgment input means for inputting a judgment as to whether the blinking light feels flickering or like continuous light to the human. A flicker frequency measuring device comprising: (3) By injecting a flashing light into a human's eyes and determining whether or not that person perceives the flashing light as flickering light,
A device for measuring critical flicker frequency as one element quantitatively expressing human visual function, comprising: a head stabilizing means for stably positioning the human head relative to the blinking light; eyepiece means that comes into contact with the person's face to prevent light other than the blinking light from entering the eyes of the person; an optotype light source that emits continuous light; and an optotype light source that emits continuous light; a light blocking means for intermittently blocking the continuous light to generate the blinking light; a blocking frequency control means for controlling the frequency at which the light blocking means blocks the continuous light; 1. A flicker frequency measuring device comprising: a flicker judgment input means for inputting a judgment as to whether the flicker is perceived as continuous light or continuous light. (4) By entering a flashing light into a human's eyes and determining whether or not that person perceives the flashing light as flickering light,
In a device that measures critical flicker frequency as one element that quantitatively represents human visual function, light other than the blinking light enters the human eye when it comes into contact with the face around the human eye. an eyepiece means for blocking the optotype, an optotype light source that emits continuous light, a light blocking means that intermittently blocks the continuous light emitted from the optotype light source to generate the blinking light; A blocking frequency control means for controlling the frequency at which the continuous light is blocked by the blocking means, a distance adjusting means for adjusting the distance from the eye to the optotype light source, and whether the blinking light feels flickering to the human. or a flicker judgment input means for inputting a judgment as to whether the flicker is perceived as continuous light or not.