Visual field measuring device

Abstract

To provide a field-of-view measuring machine that can easily and accurately measure a field-of-view range upon wearing a protector for a head, eye, or breathing.SOLUTION: A field-of-view measuring device 1 comprises: a human head model 4; and a measurement dome 3 which is disposed in a front of the human head model and in which a plane facing the human head model is a hemispherically shaped field-of-view range measuring plane 31, In the field-of-view range measuring plane, a graticule is disposed in vertical and longitudinal directions with the front defined as 0° when disposing the human head model at a measurement position at a center of a hemisphere. The field-of-view range measuring plane is provided with the graticule up to 120°in at least the longitudinal direction. The field-of-view measuring device is configured to have a CCD camera 41 provided with a fish-eye lens disposed at a position of the eye of the human head model and thereby be able to photograph the graticule of the field-of-view range measuring plane.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a visual field measuring device, and more particularly to a visual field measuring device for measuring the visual field range when wearing protective gear such as a head, eyes, or respiratory protection device.

Background Art

[0002] To protect the eyes and respiratory system from flying objects, chemical droplets, and dust generated during work, protective glasses, goggles, or masks are worn. The more severe the environment, the more the protective glasses turn into goggles or masks, covering more of the eyes from semi-face to full-face, generally resulting in a narrower field of vision. While improving the functions of goggles and masks, there is a desire to ensure the field of vision as much as possible.

[0003] It is preferable to objectively measure the visual field range when wearing such goggles or masks.

[0004] As a conventional visual field measuring device, there is known a device that uses a device in which light points distributed over the entire visual field light up, illuminates the light points with a strength having a logarithmic function step, and measures the visual field by determining whether the person to be diagnosed can see or not (see Patent Document 1).

[0005] However, this visual field measuring device has problems in that it takes too much time because the subject judges the visual field, and the measurement results vary depending on the subject.

[0006] On the other hand, in accordance with JIS T8152-1981, a method has been proposed in which a small light bulb is attached to the eye part of a standard human head having approximately the same size as that of an adult male's head, the light generated from the light bulb is projected onto a semi-spherical projection surface, the part where the light hits is regarded as the visual field, and the visual field angle is measured (see Non-Patent Document 1).

[0007] According to this method, the field of view is defined as the area illuminated by the light bulb, but it is difficult to say that the area illuminated by the light bulb is the same as a person's field of view. Furthermore, it is difficult to determine the boundary of the area illuminated by the light bulb, which leads to a large margin of error for the measurer. Generally, a person's field of view is said to be about 100° horizontally, but this measurement method can only measure up to 90° horizontally.

[0008] Furthermore, Part 11 of the ISO (International Organization for Standardization of Respiratory Protective Equipment) includes a section on visual field measurement, but the measurement principle is almost the same as JIS T8152-1981, in which a small light bulb is attached to the eye area of ​​a person's head, and the image is projected onto a hemispherical projection surface, and the area illuminated by the light is measured (see Non-Patent Literature 2).

[0009] The differences from the aforementioned technology are that the hemispherical projection surface extends up to 120° to the left and right, and the field of view mapping uses 10 predetermined points for measuring the field of view angle, with the values ​​calculated as the "Visual Field Score (VFS)".

[0010] In this case as well, the eyes on the human head are represented by light bulbs, and there is a problem in that it is difficult to say that the area illuminated by the light bulbs is the same as the human field of vision. It is difficult to determine the boundary of the area illuminated by the light bulbs, and there is a problem in that the measurement error becomes large. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 2-4307 [Non-patent literature]

[0012] [Non-Patent Document 1] Sakou, Yukio et al., "Results of Vision Tests on Personal Equipment," Fire and Disaster Management Agency Report, No. 32, 1995. [Non-Patent Document 2] ISO 16900-11 Respiratory protective devices - Methods of test and test equipment -Part 11: Determination of field of vision, 2013 [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] Non-Patent Documents 1 and 2 have the problem that the eyes on the human head are represented by light bulbs, and it is difficult to say that the area illuminated by the light bulbs is the same as the human field of vision. In addition, it is difficult to determine the boundary of the area illuminated by the light bulbs, which leads to a large error by the measurer. Incidentally, it is said that the human field of vision is about 100° horizontally, but the measurement method in Non-Patent Document 1 has the problem that it can only measure up to 90° horizontally.

[0014] In view of these circumstances, the present invention aims to provide a field of view measuring device that can easily and accurately measure the field of view when wearing protective equipment for the head, eyes, respiratory devices, etc. [Means for solving the problem]

[0015] A first aspect of the present invention that solves the above problems is a field of view measuring device comprising a human head model and a measuring dome positioned in front of the human head model, the surface facing the human head model being a hemispherical field of view measuring surface, wherein the field of view measuring surface has lines of longitude and latitude arranged in the up, down, left, and right directions with the front being 0° when the human head model is positioned at the center of the hemisphere, and lines of longitude and latitude up to 120° in the left and right directions, and a CCD camera equipped with a fisheye lens is positioned at the eye position of the human head model so that the lines of longitude and latitude on the field of view measuring surface can be photographed.

[0016] A second aspect of the present invention is a field of view measuring device according to the first aspect, wherein an illumination device is provided on the side of the human head model to illuminate the lines of longitude and latitude on the field of view measuring surface.

[0017] The third aspect of the present invention is the field of view measuring machine according to the first or second aspect, which includes a field of view measuring device that processes the image captured by the CCD camera on a personal computer and measures the field of view.

[0018] The fourth aspect of the present invention is the field of view measuring machine according to the third aspect, wherein the field of view measuring device is software that operates on a computer.

[0019] The fifth aspect of the present invention is the field of view measuring machine according to the first to fourth aspects, wherein the human head model is provided so as to be replaceable with other human head models.

[0020] The sixth aspect of the present invention is the field of view measuring machine according to the first to fifth aspects, wherein the human head model is provided so as to be movable between the measurement position and the preparation position.

Advantages of the Invention

[0021] According to the field of view measuring machine of the present invention, there is an effect that a field of view approximating the actual field of view can be easily and accurately assumed.

Brief Description of the Drawings

[0022] [Figure 1] It is a perspective view of the field of view measuring machine according to an embodiment of the present invention. [Figure 2] It is a side view of the field of view measuring machine according to an embodiment of the present invention. [Figure 3] It is a top view of the field of view measuring machine according to an embodiment of the present invention. [Figure 4] [[ID=3 | 6]]It is a front view of the field of view measuring machine according to an embodiment of the present invention. [Figure 5] It is a diagram showing the measurement flow of the field of view measuring machine according to an embodiment of the present invention. [Figure 6] It is a photograph showing an example of the measurement result of the field of view measuring machine according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0023] The present invention will be described in detail below based on embodiments.

[0024] (Embodiment 1) Figure 1 is a perspective view showing a schematic configuration of a field of view measuring device according to Embodiment 1 of the present invention, Figure 2 is a side view partially transparently showing the side view, Figure 3 is a top view thereof, and Figure 4 is a front view thereof.

[0025] As shown in these drawings, the field of view measuring device 1 comprises a measuring dome 3 placed on a base 2 and a human head model 4. The human head model 4 is placed on a stand 5, which is placed on a rail 6 and is movable in the left-right direction in Figure 2. In each drawing, the human head model 4 is shown positioned at position A, which is the measurement position located at the center of the spherical surface of the measuring dome 3, and at position B, which is the preparation position located away from the spherical surface. However, in reality, it is placed at either one or the other, and it is movable between positions A and B. In addition, at position B, goggles or other equipment to be used for field of view measurement can be attached to and detached from the human head model 4, and the human head model 4 can be rotated 90° so that it can face the operator directly.

[0026] The inner surface of the measurement dome 3, the surface facing the human head model 4, is a spherical surface that extends from the hemisphere on the left and right sides, and the inner surface of the sphere is a field of view measurement surface 31 on which lines of longitude and latitude are placed. When the human head model 4 is placed at position A, the position of the eyes is located at the center of the hemispherical cross section of the sphere, and the lines of longitude and latitude are drawn with the front as 0° and extending up, down, left and right, up to 90° on the up side and up to 120° on the left and right sides.

[0027] Since the longitude and latitude lines of the field of view measurement surface 31 require high precision, the measurement dome 3 is preferably made of a hard material such as metal or hard resin, and more preferably a material with a low coefficient of thermal expansion. In this embodiment, it is made of synthetic wood.

[0028] The human head model 4 can be swapped with a single screw between a head modeled after a standard male head and a head modeled after a standard female head, and each can be fitted with goggles, masks, face shields, etc. that humans wear. The eyes of the human head model 4 are also modeled after human eyes, and instead of eyeballs, a CCD camera 41 equipped with a fisheye lens is installed.

[0029] The CCD camera 41 is connected to a personal computer (not shown), and is capable of transmitting captured images to the computer. The CCD camera 41 does not need to be directly connected to the computer; it may be connected to the computer after shooting, or the captured images may be transferred to the computer via a memory card or similar device.

[0030] The personal computer has software installed that processes images captured by the CCD camera 41 to measure the field of view, and this software processes the images to measure the field of view, which constitutes the field of view measuring device of this embodiment.

[0031] Furthermore, the field of view measurement device does not need to be software that can be installed on a personal computer; it may be a dedicated device connected to the CCD camera 41 of the human head model 4. In this case, the dedicated device comprises a screen that displays the image captured by the CCD camera 41 and a processing unit on which software that processes the image and measures the field of view range operates.

[0032] On the side of the human head model 4, although not shown in the illustration, is an illumination device consisting of LEDs for illuminating the field of view measurement surface 31. Alternatively, the inner surface of the measurement dome 3 may be formed from a transparent material such as transparent resin, and the lines of longitude and latitude may be drawn on this transparent material, with the illumination device placed on the back side of the transparent material.

[0033] Next, we will explain the procedure for measuring the visual field using this visual field measuring device 1. First, in order to perform calibration before measuring the field of view, the human head model 4 is moved to position A without any equipment attached and placed inside the measurement dome 3, and the longitude and latitude lines drawn on the field of view measurement surface 31 are aligned with the center points, horizontal line, and vertical line of the left and right CCD cameras 41.

[0034] Next, the human head model 4 is moved to position B, and a test object such as goggles is attached to the human head model 4. Then, it is moved to position A and photographed. The image measured on the field of view measurement surface 31 is an image of the field of view narrowed by the attached test object, and this image can be viewed on the software.

[0035] Next, when you press the measurement button in the software, the software measures the field of view. Figure 5 shows the measurement flow. When measurement starts in step S1, a raw image from the CCD camera 41 is acquired in step S2, boundaries are detected by binarization of the image in step S3, and a visible line is formed in step S4.

[0036] Figure 6 shows an example of measurement results. The line around the white-looking field of view is the visible line 45, and the line larger than the visible line 45 is the standard field of view line 46, which indicates the field of view without the test specimen attached.

[0037] In this measurement state, the processing status can be confirmed on the screen, and a green visible line 45 is displayed and starts moving on the screen. The visible line 45 eventually detects the boundary between the frame and the field of view according to the measurement flow in Figure 5 and moves to the final position in Figure 6.

[0038] Once this visible line 45 is determined, step S5 displays the field of view and calculates the field of view area, and simultaneously, step S6 draws and crops the image.

[0039] Note that the field of view is continuously measured on the screen during the measurement. The field of view is the ratio of the field of view measured with the test object attached, compared to the field of view without the test object attached, which is set to 100%.

[0040] At this point, you decide whether to end the measurement (step S7). If you want to measure again (step S7; No), you return to step S2. When you press the measurement end button (step S7; Yes), the visible line 45 stops, the field of view is determined, and the measurement ends (step S8). The field of view is calculated by comparing the area of ​​the visible line 45 with the area of ​​100% field of view (standard field of view line 46). You can also check the field of view angle at a location specified with the mouse on the computer screen.

[0041] The field of view measuring device 1 described above can measure the field of view by binarizing the image measured by a CCD camera 41 equipped with a fisheye lens, thus enabling objective and accurate measurement of the field of view. Furthermore, since the field of view is measured using an image captured by a CCD camera 41 equipped with a fisheye lens instead of a conventional light bulb, it is possible to measure a field of view exceeding 100° on both the left and right sides, resulting in a more accurate measurement of the actual field of view.

[0042] Furthermore, the fisheye lens for the CCD camera 41 is acceptable even if it is a wide-angle lens, as long as it can capture a range of at least 120°. [Industrial applicability]

[0043] This device can measure the field of view for various types of equipment, including goggles, masks, face shields, swimming goggles, swimming masks, hoods, breathing apparatus, and helmets. [Explanation of Symbols]

[0044] 1…Field of view measuring device, 2…Base, 3…Measurement dome, 4…Human head model, 5…Stand, 6…Rail, 31…Field of view measurement surface, 41…CCD camera, 45…Visible line, 46…Standard field of view line

Claims

1. The device comprises a human head model and a measuring dome positioned in front of the human head model, with the surface facing the human head model forming a hemispherical field of view measurement surface. On the field of view measurement surface, lines of longitude and latitude are arranged in the vertical, horizontal, and vertical directions, with the front being 0° when the human head model is positioned at the measurement position at the center of the hemisphere. The lines of longitude and latitude extend up to 90° vertically and up to 120° horizontally. An illumination device is provided on the side of the human head model to illuminate the lines of longitude and latitude on the field of view measurement surface, and a CCD camera equipped with a fisheye lens is positioned at the eye position of the human head model so that the lines of longitude and latitude on the field of view measurement surface can be photographed. The field of view measuring device includes a head model without any attachments, which is placed at the measurement position inside the measurement dome, and the field of view calibration is performed by aligning the lines of longitude and latitude drawn on the field of view measurement surface with the center points, horizontal line, and vertical line of the left and right CCD cameras; then, with the attachments attached, the head model is placed at the measurement position, and the CCD camera captures a measurement image, which includes the measurement field of view line, and the measurement image is imported into the software. The software of the visual field measuring device measures the field of view of the attached item by using the boundary obtained by binarizing the measurement image as the measurement field of view line when the attached item is attached, and comparing this with a standard field of view line provided by the software.

2. The field of view measuring device according to claim 1, wherein the measuring dome is made of synthetic wood with a low coefficient of thermal expansion.

3. The visual field measuring device is software that operates on a computer, according to claim 1.

4. The visual field measuring device according to any one of claims 1 to 3, wherein the human head model comprises one made to resemble a standard male head and one made to resemble a standard female head, and is provided to be interchangeable.

5. The visual field measuring device according to any one of claims 1 to 4, wherein the human head model is provided to be movable between the measurement position and a preparation position for making preparations such as attaching the wearable item.

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