JP7219460B2 - Lighting device, lighting method and lighting system - Google Patents

Description

The present disclosure relates to lighting technology that makes characters and the like easier to read.

BACKGROUND ART When visual work such as reading, proofreading of texts, and drafting is performed, work efficiency decreases if the visibility (visibility) of visual objects such as characters and diagrams is low. Factors affecting clarity include the size of the visual object, the brightness of the visual object, and the brightness and color contrast between the visual object and the background (hereinafter simply referred to as contrast). can.

A magnifying glass or the like enhances visibility by enlarging a visual target, and a lighting fixture attempts to improve visibility by brightening a visual target. Although it is desirable to increase the contrast so that the elderly and people with low vision can perform visual tasks comfortably, means for increasing the contrast of characters and the like have not been put into practical use. As a technique for improving the contrast, for example, a technique of projecting a second illumination light corresponding to the shadow of the object onto an object illuminated by the first illumination light using a projector or the like has been proposed (for example, , see Patent Document 1).

Japanese Patent No. 3276637

However, although the technique disclosed in Patent Document 1 and the like emphasizes the shadow of the object, which is the visual target, the second illumination light illuminates the object, so the brightness of the visual target is also increased, which reduces the contrast. Therefore, there may be cases where the improvement in clarity is insufficient. In particular, sufficient consideration has not been given to the improvement of visibility in tasks that involve reading characters, such as reading, proofreading, and drawing. Furthermore, difficulty in reading characters due to aging and difficulty in reading characters due to fatigue or disability varies greatly among individuals, but no consideration has been given to such individual differences in viewing.

The present disclosure can be implemented as the following forms or application examples.

(1) A first aspect of the present disclosure provides an illumination device for illuminating a visual target. This illumination device includes an imaging unit that captures an image of a visual target, and a storage unit that stores a clear vision model that reflects the relationship between the ease of recognition of a visual target including characters and at least the brightness and contrast of the characters that are the visual target. a projector that projects a projection image corresponding to the captured image of the visual target onto the visual target and superimposes the projection image on the visual target; An image generation unit that recognizes at least the brightness and the contrast of a certain character and generates the projected image from the captured image using the distinct vision model so that the visibility of the visual target is within a desired range. and According to this illumination device, it is possible to improve the visibility of visual objects including characters. A "projector" is a device that projects an image, and it goes without saying that the light source and image forming method are not limited. For example, a projector that projects an image by turning on and off light sources such as xenon lamps, LEDs, and lasers using liquid crystals, etc., and a large number of minute mirrors that control the angles of the mirrors to turn on the emission of reflected light. A wide variety of projectors can be used, such as a projector using a digital mirror device (DMD) that turns off, or a projector that draws an image by controlling the direction of laser light emission at high speed with a multi-axis mirror. In addition, by combining these, the entire visible object is illuminated by a liquid crystal projector, etc., and the outside of the outline of characters, etc. in a narrow range that the user sees is illuminated by laser drawing. correspond to In addition, the term “character” used in this specification means characters in a broad sense including pictograms, pictograms, signs, signs, graphic symbols, and the like. In other words, "character" means a code created to convey meaning. characters”.

(2) In such a lighting device, the clear vision model is a model that reflects the relationship between the size, brightness, and contrast of characters that are the visual target, and experiments were conducted using subjects whose contrast sensitivity falls within a certain range. It is also possible to use a model obtained By doing so, it is possible to improve clarity using a model actually obtained using a subject.

(3) In such a lighting device, the distinct vision model may be a model constructed in advance for each group of visual characteristics to which the user using the lighting device belongs. In this way, it is sufficient to prepare a distinct vision model for each group.

(4) In such a lighting device, a display section for displaying an image for determining the visual characteristics of the user in a plurality of modes with different brightness and contrast, and the plurality of modes displayed on the display section. and a group identification unit that identifies a group of visual characteristics to which the user belongs by selecting at least one of the images. This makes it possible to easily identify the group of visual characteristics to which the user belongs when using the lighting device.

(5) In such a lighting device, the distinct vision model may be a model prepared in advance for each user who uses the lighting device. By doing so, it is possible to improve the visibility according to the individual characteristics of the user. The clear vision model can take various forms, such as a readability model based on the ease of reading characters and a detection model based on the ease of detection of visual targets.

(6) In such a lighting device, when the image generation unit determines that the visual target is moving based on the captured image of the visual target, the projected image is converted to the image that the visual target is moving. The image may be generated as an image with at least a lower contrast than in the case where it is not. By doing so, it is possible to suppress difficulty in viewing when the visual target is moving.

(7) In such an illumination device, the image generation unit may generate the projection image by performing anti-aliasing on edges included in the captured image. In this way, even when the resolution of the visual target is higher than the resolution of the projector, it is possible to realize an easy-to-view display.

(8) Such a lighting device includes a head section in which the imaging section and the projector are incorporated, and a stand section for supporting the head section. The imaging unit may capture an image of a range in which the visual object may be placed, and the projector may superimpose the generated projection image on the visual target placed in the predetermined range. . In this way, each of the lighting devices described above can be easily realized in a practical form.

(9) In such a lighting device, the visual recognition position specifying unit that specifies a position on the visual target visually recognized by the user is provided, and the image generating unit generates the image from the captured image of the specified position on the visual target. , to generate the projection image. By doing so, the range for generating the projection image can be narrowed, and the processing can be simplified. Moreover, since the projection range of the projector can be narrowed, power saving can be achieved. Alternatively, it becomes easy to increase the contrast. The range in which the user visually recognizes the visual object is rather narrow. It is known that the central visual field is limited to a field angle range of about several degrees. For this reason, a viewing position specifying unit is provided that captures the position and direction of the user's pupils with a camera and recognizes the direction of the user's line of sight. A sufficient effect can be obtained in terms of improving the readability by making it a target to be performed. In addition to this, the visible position specifying unit may be configured to guide the visible position with an LED or the like, and to specify the position that guides the reading as the visible position.

(10) A second aspect of the present disclosure provides an illumination method for illuminating a visual object. In this illumination method, a visual object is imaged, a clear vision model reflecting the relationship between the easiness of recognition of the visual object including characters and at least the brightness and contrast of the characters as the visual object is stored in advance, and the visual object is recognizing at least the brightness and contrast of the character, which is the visual target, from the captured image, and using the clear vision model to set the clarity of the visual target within a desired range, from the captured image to a projected image is generated, and the projection image is projected onto the visual target using a projector, thereby superimposing the projection image on the visual target. By doing so, it is possible to improve the visibility of visual objects including characters.

(11) A lighting system is provided as a third aspect of the present disclosure. This lighting system includes a first lighting device that is the lighting device described above, and a second lighting device that is provided separately from the first lighting device and that illuminates a predetermined range using a projector. is. Here, the second illumination device illuminates a range different from the range illuminated by the first illumination device and wider than the illumination range of the first illumination device, and the illumination is obtained by imaging the illumination range. analyzing the range image to generate an edge-enhanced image that emphasizes edges of the illumination range image; projecting the edge-enhanced image by the projector of the second illumination device; and projecting the edge-enhanced image on the illumination range. superimpose. In this case, the edge refers to a boundary portion, such as a stair nosing, which needs to be conspicuous in order to improve the safety of the living environment. According to this illumination system, not only the visual object including characters but also the edges of objects existing in a wide range are highlighted, so that the visibility of the entire environment including the visual object including characters can be enhanced.

1 is a schematic configuration diagram of a lighting device according to a first embodiment; FIG. FIG. 2 is a block diagram showing the internal configuration of a video processing unit; Explanatory drawing which shows an example of the image projected. FIG. 5 is an explanatory diagram illustrating the relationship between background luminance and luminance contrast and readability level; FIG. 4 is an explanatory view showing a measuring device having an internally illuminated circular optotype used for measuring contrast sensitivity. FIG. 4 is an explanatory diagram showing the contents of independent variables “character size (dimension),” “brightness contrast,” and “background brightness.” FIG. FIG. 10 is an explanatory diagram showing the readability model (average value) of the subjects of group 1, with 10 points, 14 points, and 21 points selected as the character size. FIG. 10 is an explanatory diagram showing the readability model (average value) of the subjects of group 2 by selecting 10 points, 14 points, and 21 points as the character size. FIG. 10 is an explanatory diagram showing the readability model (average value) of the subjects of group 3, with 10 points, 14 points, and 21 points selected as the character size. Explanatory drawing which shows the method of selecting a distinct vision model simply. FIG. 4 is an explanatory diagram for explaining character anti-aliasing processing; The schematic block diagram which shows 2nd Embodiment.

A. First embodiment:
FIG. 1 is a schematic configuration diagram of a lighting device 100 according to the first embodiment. The lighting device 100 includes a lighting unit main body 20 incorporating a video camera 10 and a projector 40 corresponding to an imaging unit, and a stand 51 supporting the main unit above a base portion 52 . The video camera 10 can take an image of the placement space for materials, etc. on the base portion 52 . The video camera 10 has a resolution capable of capturing so-called 4K images. The video camera 10 includes an autofocus mechanism that automatically focuses on the material TX on the base portion 52 and an automatic aperture mechanism that automatically adjusts the brightness of an image to be picked up. Furthermore, the video camera 10 has a free pan head 15 that controls the imaging direction and magnification.

This free camera platform 15 controls the posture of the video camera 10, that is, tilt and pan. The free pan head 15 also has a magnification of the video camera 10, that is, a zoom function. Therefore, the position and size of the material TX placed on the base portion 52 are automatically determined, and if the material TX is A4 size, for example, the outer shape of the material TX is optically zoomed so as to be the imaging range. At this time, if the document TX is not placed at the center of the base section 52 but at a biased position, the video camera 10 is tilted and panned using the illumination section main body 20 and the free camera platform 15 to capture the image. Change position. Since these various mechanisms and functions are well-known techniques for video cameras, detailed description thereof will be omitted.

The illumination section main body 20 includes an image input section 21 for inputting an image captured by the video camera 10 , an image processing section 30 for processing this image, and an image output section 23 for outputting the processed image to the projector 40 . The video input unit 21 has a function of performing keystone correction on the image obtained by the video camera 10 . Keystone correction here means that when the image of the document TX captured by the video camera 10 is distorted into a trapezoidal shape in at least one of the vertical and horizontal directions because it is not facing the video camera 10, it is corrected to the image of the facing position. , that is, the function of correcting an image without distortion. Since the video camera 10 and the projector 40 cannot physically be placed at the same position, the images are temporarily positioned facing each other in order to correct the difference in the physical positions between the imaging and the projection. Corresponding to this, the video output unit 23 has a function of inversely transforming the shape of the projected image. The image input unit 21 and the image output unit 23 consider the positional deviation between the video camera 10 and the projector 40 when converting the shape of the image, and convert the image captured by the video camera 10 and the image projected by the projector 40. The image is processed so as to be exactly the same on the base portion 52 .

Since the video camera 10 is capable of capturing 4K images, its resolution is 3840×2160 pixels. Assuming that a document of about A4 size (297 mm×210 mm) is captured, the image can be captured with a resolution of about 300 dpi. Similarly, the projector 40 also has 4K specifications and can project an image with the same number of pixels. The maximum brightness of the projector 40 in this embodiment is approximately 2000 lumens.

Like the video camera 10, this projector 40 also has a free camera platform 45. - 特許庁Therefore, the illumination unit main body 20 uses the pan head 45 to tilt and pan the posture of the projector 40 to change the projection position, and further uses the zoom function to adjust the size of the image to be projected. Therefore, the illumination section main body 20 can control the position and size of projection by the projector 40 to a desired position and size.

In this embodiment, the user PS of the lighting unit main body 20 appropriately places the material TX on the base unit 52 of the lighting device 100 and reads it. In order to set the resolution of the imaging and projection realized by the video camera 10 and the projector 40 to about 300 dpi, it is assumed here that the document TX of about A4 size is read. If it is a pixel), it is possible to handle materials up to a size of about A3 horizontal with the same resolution. Of course, a video camera 10 or projector 40 with a higher number of pixels may be used, or if a lower resolution is to be used, a video camera 10 or projector 40 with a smaller number of pixels may be used.

FIG. 2 is a block diagram showing the internal configuration of the video processing unit 30. As shown in FIG. An image processing unit 30 corresponding to an image generation unit includes an ocular optical nerve model conversion unit 31, a legibility model reference unit 33, a contrast enhancement unit 34, an additional image processing unit 35, an individual vision database 36 corresponding to a storage unit, An imaging/projection control unit 38 is provided. A visual data input/selection unit 60 provided outside the video processing unit 30 is connected to the individual visual database 36 . The imaging/projection control unit 38 is connected to the pan head 15 and 45, analyzes the input image Vin input from the video input unit 21, controls the attitude and magnification of the video camera 10 described above, and The attitude and projection magnification of the projector 40 are controlled.

The ocular optical nerve model conversion unit 31 receives the input image Vin input from the image input unit 21 and converts it into an optical image based on the ocular optical nerve model. The video signal that the video input unit 21 receives from the video camera 10 is a so-called moving image. Output to the conversion unit 31 . The ocular optical nerve model conversion unit 31 converts this into a retinal image Vr.

In this embodiment, a light curtain brightness model is applied as an eye optical nerve model. The light curtain brightness model is a model of a phenomenon that when light from an object that the user PS is looking at enters the eyeball, the light is scattered to form a light curtain, resulting in difficulty in seeing. The mechanism by which such a light curtain is generated is as follows. Light entering the eye is scattered by the cornea and lens. If the crystalline lens does not develop cataracts, it can be regarded as transparent to visible light, but it is an organic substance, and specifically, it is composed of minute fibrous cells. As the lens ages, the number of protein particles inside the lens increases and these become denatured. When minute protein particles increase in the lens, the lens becomes cloudy like frosted glass (cataract). Light that enters the eyeball is scattered by the lens. This scattered light creates a curtain of light in the field of view, increasing the brightness of parts of the field of view. This is the light curtain luminance.

In general, the contrast C between a visual object such as a character and its background is obtained by the following equation (1).
C=(Lt−Lb)/Lb (1)
Here, Lt is the visual target luminance and Lb is the background luminance. When a light curtain is applied to this, the contrast C of the object changes to the contrast C' of the following equation (2).
C′={(Lt+Lv)−(Lb+Lv)}/(Lb+Lv)
= (Lt-Lb)/(Lb+Lv) (2)
Here, Lv is the luminance due to the light curtain. As can be seen by comparing equations (1) and (2), as the light curtain luminance Lv increases by the amount added to the denominator, the contrast C' becomes smaller than the contrast C when the light curtain luminance is not considered. In other words, the greater the scattering caused by the crystalline lens and the like and the greater the light curtain luminance Lv, the lower the contrast and the clearer the visibility of the visual target (here, the material TX) seen from the user PS.

In addition, when measuring eye characteristics such as contrast sensitivity, which will be described later, or when evaluating the definition of an image, the contrast in a visual object with a striped pattern such as a sine wave or rectangular wave with continuous light and dark is expressed by the following equation (3 ).
C=(Lmax−Lmin)/(Lmax+Lmin) (3)
where Lmax is the maximum luminance of the stripe pattern and Lmin is the minimum luminance of the stripe pattern. When a light curtain is applied to such a striped visual object, it can be seen that the contrast is lowered and the visibility is lowered, as in the case of Equation (2), as expressed by the following equation.
C'=(Lmax−Lmin)/(Lmax+Lmin+Lv) (4)
Hereinafter, the definition of equation (1) is used for the contrast of the visual object, and the definition of equation (3) is used for contrast sensitivity.

In general, the light curtain luminance Lv is obtained by the following equation (5).
Lv=aE/θ ² (5)
where E is the illuminance at the eye position, θ is the angle between the light source and the visual object, and a is the coefficient. The coefficient a takes a value according to the intensity of scattering in the lens. The intensity of scattering in the crystalline lens depends on the state of the crystalline lens, as described above, and thus differs depending on the user PS. Therefore, the coefficient a for each user PS may be stored in the individual vision database 36, and the light curtain luminance Lv may be calculated for each user PS to obtain the ocular optical nerve model. Equation (5) shows that if the user PS is the same, the illuminance at the eye position of the user PS due to the light from the light source is high, and the distance between the visual object that the user PS is trying to see and the light source is The smaller the angle, the larger the light curtain luminance Lv. If the document TX has black characters printed on white paper, the white part without characters acts as a light source that reflects the light of the illumination. can be obtained by integrating over the angle θ around where the user PS is gazing.

The magnitude of the light curtain luminance Lv is affected by the eye optical nerve model of the user PS, for example, the opacity of the lens. Therefore, the coefficient a is originally determined for each user PS. Of course, since the opacity of the lens is proportional to age to some extent, age-specific models may be prepared so that the ocular optical nerve model can be switched not for each individual but for each age. Alternatively, several ocular optical nerve models may be prepared and the user PS may select one. Since the user PS cannot recognize his or her own eye optical nerve model, the user PS prepares a plurality of eye optical nerve models. , an ocular optical nerve model that is most easily seen is selected and stored in the individual vision database 36 as the ocular optical nerve model of the user PS. Of course, conversion using the ocular optical nerve model is not essential, and processing may be performed using only the readability model described below.

When the readability model reference unit 33 receives the retinal image Vr obtained by converting the input image Vin according to the ocular optical nerve model conversion unit 31 reading from the individual vision database 36 and setting the ocular optical nerve model, the readability model reference unit 33 converts the retinal image Vr The readability model of the user PS stored in the individual vision database 36 is referred to using the brightness and contrast of .

The readability model stored in the individual vision database 36 will be described with reference to FIG. FIG. 3 exemplifies a part of the material TX in which characters and line drawings are described. The material TX is printed with black ink on uncolored paper. Assume that the image ORG is obtained by illuminating this with an illumination device having a color temperature of 5200 Kelvin and setting the luminance on the material TX to 1000 cd/m ² . On the other hand, the images PG1 and PG2 are assumed to be images whose brightness on the material TX is set to 50 cd/m ² and 200 cd/m ² respectively by changing the brightness of the illumination device while keeping the color temperature unchanged. . As shown in the figure, even with the same material TX, if the brightness of the background color portion is lowered, the legibility is lowered. The brightness of the character portion is originally low, and even if the illumination is brightened, the brightness hardly changes. For this reason, if the entire document TX is illuminated brightly and its luminance (hereinafter referred to as background luminance) is increased, the luminance contrast generally increases.

The readability of the material TX is affected by three factors: the size of the visual object, the brightness of the visual object (background luminance), and the contrast between the visual object and the background (brightness contrast). When the user PS reads the material TX, the illumination device cannot change the size of the visual object, that is, the number of character points. In this embodiment, based on this point, the illumination device changes the background luminance (brightness) of the visual target and the luminance contrast. Such a process was derived from experimentally determining how the legibility of a visual object for the user PS changes by changing the background luminance and luminance contrast of the visual object. The inventors conducted experiments on the readability of TX, which is a visual target, using a large number of subjects, and organized the results. FIG. 4 shows an example of the relationship between background luminance, luminance contrast, and readability level based on experimental results.

This FIG. 4 is extracted by conducting the following experiment. Thirty-seven male and female subjects between the ages of 60 and 85 participated in the experiment. Subjects were given contrast sensitivity measurements prior to the experiment. For the measurement of contrast sensitivity, a measurement device (CSV-1000E) having an internally illuminated circular optotype (0.87 degrees of vision) printed with sinusoidal waves having different brightness contrasts and spatial frequencies, as shown in FIG. 5, was used. Using. In this case, since the measurement is performed using a striped visual object, the contrast when measuring the contrast sensitivity was calculated using the above equation (3). The contrast sensitivity was determined as the reciprocal of the threshold brightness contrast (50th percentile value brightness contrast). This circular optotype was placed in a cuboid box-shaped booth with a height of 1800 mm, a width of 1500 mm and a depth of 1700 mm, the inside of which was painted white. rice field. A chin rest was provided to maintain a constant distance from the target. The illuminance in the booth was monitored to keep the brightness constant throughout the experiment.

Outside light was prevented from entering the cuboid box-shaped booth. As shown in FIG. 6, in the experiment, "character size (dimension)", "brightness contrast", and "background brightness" were used as independent variables. The breakdown of each independent variable is as shown. The independent variable is the clear vision triplet. Each independent variable had 4 levels. Therefore, there were 64 experimental conditions. The dependent variable was the readability level L and was defined as follows.
L = 1: Unreadable L = 2: Hard to read L = 3: Somewhat difficult to read but readable L = 4: Readable without effort L = 5: Easy to read L = 6: Very easy to read

In the experiment, each subject sat in front of the opening of the experimental booth, placed their chin on the chinrest, and maintained a constant distance to the target. In this state, the experimenter looked at the target posted on the front wall inside the booth through the opening of the experiment booth. The target was previously set to one of 64 conditions. The subject observed the visual target in the booth for 1 minute, adapted to the brightness, and then orally evaluated the readability of the visual target according to the instructions of the experimenter. Therefore, it can be recognized that the background luminance was adapted luminance for the subject.

The above procedure was repeated for 64 visual targets. The results of the experiment showed variability in the readability ratings among individuals. Therefore, the subjects were divided into three groups according to their contrast sensitivity. The range of contrast sensitivity for the three groups is as follows.
Group 1: 0.33-1.18 (9 people)
Group 2: 1.19-1.40 (20 people)
Group 3: 1.41-1.64 (8 people)
For each group, the readability ratings of the subjects were averaged for each of the 64 conditions. As a result, in each of the three groups classified by contrast sensitivity, readability was evaluated for each of 64 conditions, which were a combination of 4 conditions for character size, 4 conditions for brightness contrast, and 4 conditions for background brightness. Average values were obtained. The brightness contrast of characters is defined by Equation (1).

In each of Groups 1 to 3 classified according to the above contrast sensitivity, the average value of the readability evaluation obtained for each of 64 conditions combining 4 conditions of character size, 4 conditions of brightness contrast, and 4 conditions of background brightness. was used to create a readability model according to the following procedure.
1) Extraction of 50th percentile value For the data of subjects classified into groups with different contrast sensitivities (group 9 persons, group 2 20 persons, group 3 8 persons), for each of the four character sizes , for each of the four background luminances, and for each of the four luminance contrasts, the 50th percentile value of the readability rating was determined. Specifically, the horizontal axis represents the evaluation values from 1 to 6, and the vertical axis represents the cumulative ratio (%) of subjects who selected each evaluation value. The cumulative ratio draws a probability curve that gradually increases from an evaluation value of 1. A regression equation for the probability curve was determined and used to read the 50th percentile value (3 groups x 64 conditions).

In the above experiment, the character size was also treated as an independent variable, but in the illumination device 100 of this embodiment, the character size itself cannot be changed. The illumination device 100 is intended to improve readability by controlling the background brightness and brightness contrast applied to the visual target of characters of a given size. Therefore, from the readability approximation surface obtained above, readability that is considered to be obtained for various combinations of luminance contrast and background luminance for each contrast sensitivity group and for each character size is calculated. Converted to an obtainable model. Although the details of the conversion are omitted, for each of Groups 1 to 3, approximations of readability were obtained for 16 combinations of 4 conditions of luminance contrast×4 conditions of background luminance for each character size. Figures 7A, 7B, and 7C show 10, 14, and 21 point sizes of characters that appear frequently in newspapers and books from among the 16 data obtained, and the readability model is calculated. is shown. In FIGS. 7A-7C, the numerical values of the contour lines correspond to the legibility levels L (1-6) described above.

Based on the above experimental results, FIG. 4 described above shows an example of a simple model of clear vision in order to explain the processing of the illumination device 100 . FIG. 4 shows data obtained using subjects in the above-described experiment as a relationship between background luminance and luminance contrast with readability as a parameter. In the experiment, the readability was measured by changing the size of the characters on the material TX, the background brightness, and the brightness contrast. FIG. 4 shows the readability when the background brightness and brightness contrast are changed while the character size is fixed at 14 points based on the experimental results. FIG. 4 corresponds to a clear vision model that reflects the relationship between the ease of recognition of visual objects including characters and at least the brightness and luminance contrast of characters that are visual objects.

In FIG. 4, the luminance contrast C on the horizontal axis is defined by the following equation (6) using the background luminance Lb and the target luminance Lt.
C=(Lb−Lt)/Lb (6)
The background luminance Lb is the luminance of the paper (white) portion, and the target luminance Lt is the luminance of the character (black) portion printed on the paper (the unit for both is candela cd/m ² ). Luminance was measured using a luminance meter. For a portion with a small area on paper, such as 14-point characters, it may be measured using a two-dimensional luminance meter. The target luminance Lt may be obtained by measuring the luminance of the part.

FIG. 4 was created based on the data of the subjects of Group 2, but in Group 1, the graph shifted to the upper right direction, and in Group 3, the graph shifted to the lower left direction, but the background luminance Lb and the luminance contrast C, in other words, the shape of the graph of the legibility level L showed the same tendency. In the graph of a certain legibility level L, the slope in the direction of the background luminance Lb was nearly vertical, and the slope in the direction of the luminance contrast C was gentle compared to this. From this, for example, at a point P1 having a predetermined background luminance Lb and a predetermined luminance contrast C, the readability for a certain subject in group 2 is level L=3, that is, it is somewhat difficult to read, but can be read. When trying to make this level L = 4, that is, to be able to read without difficulty, it cannot be achieved only by increasing the background luminance Lb by the lighting device, but by increasing the luminance contrast C, the point P2 It turns out that it can be achieved with background luminance and luminance coton last. This relationship is the same when going from another legibility level L to a more legible level L+1.

Although FIG. 4 shows the average values of experimental data for subjects in group 2, it is also possible to obtain and use data corresponding to FIGS. 7A to 7C for individual users using lighting device 100. The individual vision database 36 may store average data of persons belonging to each group, or may store individual data. In other words, the "individual visual data" referred to here may be data of a specific individual, or visual data may be classified and stored as representative visual data for each category.

The video processing unit 30 shown in FIG. 2 uses the relationship illustrated in FIG. 4 to perform illumination as follows. First, the video camera 10 provided in the lighting section main body 20 images the material TX on the base section 52 . The image captured by the video camera 10 is input to the image input unit 21 and input to the lighting unit main body 20 as the input image Vin. The input image Vin is input to the imaging/projection control unit 38 together with the eye optical nerve model conversion unit 31 . The imaging/projection control unit 38 uses the pan head 15 and 45 to control the attitude and zoom of the video camera 10 and the projector 40 described above.

On the other hand, the ocular optical nerve model conversion unit 31 converts the inputted input image Vin into a retinal image Vr using the ocular optical nerve model. Various modes are possible for the ocular optical nerve model to be used at this time. For example, the following aspects can be considered.
[1] The ocular optical nerve model of the user PS of the illumination device 100 is stored in the individual vision database 36 and applied according to the user PS. Various methods can be used to determine the user PS, such as face recognition of the user PS, visual data input by the user PS, input by the selection unit, and determination by an ID card.
[2] A plurality of ocular optical nerve models are prepared in advance, and from among these, the one that is closest to the ocular optical nerve model of the user PS is selected by the user PS using the visual data input/selection unit 60. used.
[3] Do not use the ocular optical nerve model. In this case, the input image Vin is output as it is.

The ocular optical nerve model conversion unit 31 converts the input image Vin into a retinal image Vr using the selected ocular optical nerve model. The converted retinal image Vr is input to the readability model reference unit 33 , and the readability model reference unit 33 reads out the readability model (clear vision model) of the user PS from the individual vision database 36 . The readability model is the model shown in FIG. At this time, which readability model to use may be selected for each user PS, or may be selected from a plurality of prepared readability models. You may choose one that approximates the ease model. Alternatively, as an example is shown in FIG. 8, a character of a predetermined size is displayed from the projector 40 on the spot with a predetermined brightness and brightness contrast, and the user PS inputs the readability level L. , thereby selecting the readability model. In such a case, as shown in FIG. 8, a code such as "ABC..." or "Ai..." is attached to the row/column of the sample, and the displayed characters are labeled with, for example, "A... L = 1 (unreadable), B ah L = 2 (difficult to read), ..., C ah L = 4 (can be read without difficulty)". to enter or select a readability level. By doing so, it is possible to function as a group identification unit that identifies the group to which the user belongs, or to identify individual visual characteristics.

The readability model reference unit 33 refers to the readability model corresponding to the user PS, determines how much the readability should be improved according to this readability model, Indicate to emphasize C. The contrast enhancement unit 34 obtains how much the brightness contrast C of the retinal image Vr should be increased, and determines the brightness of the image to be superimposed and projected on the material TX by the projector 40 .

4, the illumination device 100 recognizes the background brightness and brightness contrast of the material TX from the image captured by the video camera 10, and further refers to the readability model for the user PS. is not operating, the readability is level L=3, which corresponds to the state of point P1. You will be asked for That is, by superimposing exactly the same image as the imaged input image Vin on the material TX by the projector 40, the luminance (background luminance) of the white background portion of the paper is increased by the image from the projector 40, and the black character portion is superimposed. does not increase the luminance by the projector 40, the luminance contrast C of the image of the material TX can be increased. At this time, since the background luminance is also increased, the background luminance and luminance contrast of the material TX as seen from the user PS are not in the state of point P2 but in the state of point P3. In any case, the readability of the material TX as seen by the user PS is improved.

In this embodiment, the illumination section main body 20 converts the retinal image Vr into an image for enhancing the luminance contrast by the contrast enhancement section 34, and then performs additional image processing by the additional image processing section 35. FIG. This additional image processing need not necessarily be performed. In that case, the image for enhancing the luminance contrast by the contrast enhancing section 34 is directly output to the projector 40 as the output image Vout.

B. Additional image processing:
Additional image processing includes the following processing.
(1) If it is determined by analyzing the image captured by the video camera 10 that the captured image is not stationary, that is, that the material TX is moving, the captured image is A process that produces an image with at least less luminance contrast than In this way, when the material TX is being moved, the image projected by the projector 40 follows the movement, but since the brightness contrast is lowered at that time, the material TX displayed as moving for the user PS. The appearance becomes one with low brightness contrast, and discomfort is alleviated. The brightness contrast may be reduced by turning off the illumination provided by the projector 40, by reducing the brightness of the projector 40, or by applying a uniform contrast to the image displayed by the projector 40 that is not related to the image captured by the video camera 10. making it an image of brightness, and so on.

(2) anti-aliasing processing for edge portions included in the image captured by the video camera 10; Since the projector 40 forms an image with dots (on/off points of light), regardless of the resolution, boundary lines that do not match the direction in which dots are arranged in the projector, that is, oblique line segments, are shown in FIG. As a result, the line segment to be represented does not match the line of dots. In this embodiment, a 4K image is captured by the video camera 10 and projected by the projector 40, so the resolution for displaying an image of about A4 size is about 300 dpi. On the other hand, if the document TX is a printed matter, the resolution of the printed matter may be higher than 300 dpi. Therefore, if the image projected by the projector 40 as illumination includes characters or diagonal lines, and if the arrangement of the dots formed by the projector 40 does not match the vertical and horizontal directions of the dots formed by the projector, the dots are arranged vertically and horizontally. Anti-aliasing reduces the brightness of the dots on either side of the area where the increases or decreases. In this way, the user PS can visually recognize the boundaries of the oblique line segments smoothly, thereby improving the visibility of objects including many oblique line segments, such as characters. This effect is more pronounced when the resolution of the image handled by lighting device 100 is low. The effect is also great when the resolution of the projector 40 that forms the image is lower than the resolution of the video camera 10 that captures the image.

According to the first embodiment described above, the readability of the material TX can be improved by appropriately increasing the background luminance and luminance contrast of the material TX, which is the visual target. At this time, the illumination device 100 changes the background luminance and the luminance contrast based on the readability model (clear vision model), so that the readability can be improved according to the user PS. In addition, in the first embodiment, the retinal image vr is obtained and processed by using the ocular optical nerve model of the user PS. can be done. Note that the ocular optical nerve model may not be used.

C. Second embodiment:
Next, a second embodiment will be described. FIG. 10 is a schematic configuration diagram showing the second embodiment. In the second embodiment, an integrated controller 200 is provided to constitute a lighting system that controls the lighting device 100 described in the first embodiment and a lighting device that illuminates the entire environment such as a room. Integrated controller 200 controls lighting device 100 and projector 210 attached to ceiling 240 . The ceiling 240 is also provided with conventional lighting fixtures 250,260. The projector of illumination device 100 and projector 210 illuminate different illumination ranges.

In the second embodiment, the projector 210 emphasizes edges and the like that are necessary in living environments. A staircase 270 is illustrated in FIG. The integrated controller 200 displays an image in which the edge SS1 of the upper surface of each step of the staircase 270 is brightened and the edge SD1 of the upper surface of the lower step is not illuminated so that the edge of the staircase 270 can be easily recognized. , is projected using the projector 210 . Therefore, the brightness of the edge SS1 of the top surface of the steps of the staircase 270 is high, and the brightness contrast of the edges is also high. As a result, the user PS2 who uses the stairs 270 can easily see the positions of the steps of the stairs 270 . In this case, since the position of the stairs 270 does not move, the image to be projected by the projector 210 is prepared in advance and is not captured by the video camera. Of course, if the use of movable furniture such as a stepladder is assumed, a video camera may be provided on the ceiling 240 to capture the environment and emphasize the necessary edges. Alternatively, a video camera may be prepared to capture images of a room or the like, capture images of the environment to which the user PS2 moves, and control the location where the projector projects so as to emphasize the edges of the movement. In this case, the video camera or projector may be provided with the free camera platform used in the first embodiment, and the imaging range and projection range may be changed following the movement of the user PS.

Furthermore, in the second embodiment, since the integrated controller 200 also controls the illumination device 100, when the user PS1 tries to read the material TX, etc., the readability is adjusted according to the visual characteristics of the user PS1. Therefore, the same effect as in the first embodiment can be obtained, and the usage environment of the user can be comprehensively made easy to see. In other words, the user can seamlessly enjoy the environment of clear vision, from moving to a place where the material TX is read in the environment to reading the material TX.

D. Other embodiments:
(a) In the above embodiment, the readability characteristics of the individual user (see FIG. 4) were used as the clear vision model, but this characteristic does not include the character size parameter, and the data capacity is reduced. On the other hand, the distinct vision model may include the character size, and the distinct vision model may be provided as characteristic data for each character size, for example. In this case, the image captured by the video camera is analyzed to recognize the size of the characters, and the background luminance of the image projected by the projector ( (brightness of portions other than characters) and brightness contrast may be determined. The size of characters for the user changes depending on the distance between the user and the material. is determined, and characteristic data for each character size is referred to. Of course, if the distance between the material TX and the user PS is fixed, the readability model may be selected according to the recognized character size.

(b) The lighting device 100 is of the stand type, but may be of a ceiling-mounted type or a so-called pendant type that hangs down from the ceiling. The video camera and the projector do not necessarily have to be integrated, and one may be provided on the ceiling and the other as a stand type. In either case, it is sufficient if the target illuminated by the projector can be specified.

(c) In the above embodiment, the image captured by the video camera 10 is converted into a retinal image using the user's ocular optical nerve model. good too. Also, the image recognized by the user may be handled as an image other than the retinal image. For example, the image may be treated as an image whose brightness is lowered according to the age of the user.

(d) In the above embodiment, the effects of light sources other than the projector 40 of the lighting device 100, that is, light from lighting fixtures installed on the ceiling, and outdoor light coming in through windows are not taken into consideration as constant. The background brightness itself due to the light of another light source that illuminates the TX may also be adjusted. For example, taking FIG. 4 as an example, if the light from the lighting equipment on the ceiling or the light from the outdoors is strong and the background luminance is originally high, superimposing the image from the projector 40 on this will cause the background luminance to become excessive. If it is assumed that the user PS may feel glare, reduce the amount of light from the ceiling lighting fixtures, or lower the window blinds or shutters to limit outdoor light. Therefore, the background brightness due to light other than the projector 40 is once lowered, and then the image projected by the projector 40 is superimposed to improve readability. Such correspondence can be easily realized if the integrated controller 200 is provided as in the second embodiment and the amount of light of the lighting fixtures 250 and 260 can be adjusted by the integrated controller 200 .

(e) Improving the readability level L can be achieved in various ways. For example, the background luminance and the luminance contrast may be adjusted so that the readability is uniformly L=4 or more, or the readability level L before superimposition of the projected image by the projector 40 may be adjusted by a predetermined range. , for example, by a value of one. Alternatively, at least the level L may not be less than 3. Also, how to improve readability for each user PS may be stored in the individual vision database 36, and the brightness of the projected image may be determined by referring to this. The eye optical nerve model and the readability model (clear vision model) do not necessarily need to be stored together in the individual vision database 36, and may be stored in different storage units. Alternatively, it may be distributed and stored on the network, and may be referred to as needed. In this case, each individual may manage his/her own ocular optical nerve model, legibility model, and the like.

(f) The shape of characters and the like included in the projection image projected by the projector 40 is basically the same as the shape of the characters and the like included in the image captured by the video camera 10, but the user PS may If you do not instruct improvement, you may make it work as a simple lighting fixture. Also, if the material TX includes parts other than characters, such as a photograph, the area of the photograph may be recognized, and the background luminance and luminance contrast may be different for the photograph part. For example, when a photograph is displayed in gray scale like gravure, the entire photograph may be uniformly illuminated to increase only the background luminance. On the other hand, when a photograph is formed by halftone dots as displayed in a newspaper or the like, the background luminance and luminance contrast may be determined in the same manner as characters, and the projection image may be superimposed.

(g) In the above embodiment, the background brightness and brightness contrast of the entire material TX of about A4 size are adjusted to improve readability. The range is quite narrow compared to A4 document size. It is known that the central visual field is limited to a field angle range of about several degrees. For this reason, a viewing position specifying unit is provided, the position and direction of the user PS's pupils are imaged by a camera, the line of sight direction of the user PS is recognized, and only characters or the like existing in the line of sight direction, that is, the viewing position are easily read. There is no problem in making it a target for improving the quality. In this case, the range in which the background luminance and the luminance contrast are improved is narrowed, so the number of projection pixels of the projector 40 can be reduced to less than 4K. Also, the brightness of the light source of the projector 40 can be suppressed. Since such a projector with a small number of pixels and reduced brightness can be easily miniaturized, it is possible to mount the projector on the head of the user or incorporate the illumination device 100 into glasses. By using a projector with a large number of projected pixels and a bright light source, and by superimposing the projected image in a narrow range corresponding to the central visual field, the ability of the projector can be combined with the resolution of the projected image and the background luminance and luminance contrast. It may also be used to expand the range in which the increase in is performed. In order to increase the contrast in such a narrow position, a method of drawing with a laser beam may be used to draw the outside of the outline of a character or the like with a laser beam by a vector method.

(h) In each of the above embodiments, part of the configuration implemented by hardware may be replaced with software. At least part of the configuration implemented by software can also be implemented by a discrete circuit configuration. In addition, when part or all of the functions of the present disclosure are realized by software, the software (computer program) can be provided in a form stored in a computer-readable recording medium. "Computer-readable recording medium" means not only portable recording media such as flexible disks and CD-ROMs, but also various internal storage devices such as RAM and ROM, and fixed to computers such as hard disks. It also includes an external storage device. That is, the term "computer-readable recording medium" has a broad meaning including any recording medium capable of fixing data packets instead of being temporary.

The present disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from the scope of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in the respective modes described in the Summary of the Invention column may be used to solve some or all of the above problems, or Substitutions and combinations may be made as appropriate to achieve part or all. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

TX: data, Vin: input image, Vout: output image, Vr: retinal image, a: coefficient, 10: video camera, 15: free camera platform, 20: main body of lighting unit, 21: video input unit, 23: video output Part 30... Image processing part 31... Ocular optical nerve model conversion part 33... Readability model reference part 34... Contrast enhancement part 35... Additional image processing part 36... Individual vision database 38... Imaging/ Projection control unit 40 Projector 45 Free camera platform 51 Stand 52 Base unit 60 Visual data input/selection unit 100 Lighting device 200 Integrated controller 210 Projector 240 Ceiling 250, 260... Lighting equipment, 270... Stairs

Claims (11)

A lighting device for illuminating a visual object, comprising:
an imaging unit that images a visual target;
a storage unit that stores a clear vision model that reflects the relationship between the ease of recognition of visual objects including characters and at least the brightness and contrast of the characters that are the visual objects;
a projector that projects onto the visual target a projection image corresponding to the picked-up image of the visual target and superimposes the projection image on the visual target;
At least the brightness and the contrast of characters, which are the visual target, are recognized from the captured image of the visual target, and the clear vision model is used to set the clarity of the visual target within a desired range. and an image generator that generates the projected image from a captured image. The lighting device according to claim 1,
The clear vision model is a model that reflects the relationship between the size, brightness, and contrast of characters, which are the visual objects, and is a model experimentally obtained using subjects whose contrast sensitivity falls within a certain range. lighting device. The lighting device according to claim 1 or claim 2,
The clear vision model is a model constructed in advance for each visual characteristic group to which the user using the lighting device belongs. The lighting device according to claim 3,
a display unit that displays an image for determining the visual characteristics of the user in a plurality of modes with different brightness and contrast;
and a group identification unit that identifies a visual characteristic group to which the user belongs by selecting at least one of the plurality of mode images displayed on the display unit. The lighting device according to claim 1 or claim 2,
The clear vision model is a lighting device that is a model prepared in advance for each user who uses the lighting device. When the image generation unit determines that the visual target is moving based on the captured image of the visual target, the image generation unit makes the projected image have at least a higher contrast than when the visual target is not moving. 6. An illumination device according to any one of the preceding claims, wherein the illumination device is produced as a relaxed image. The lighting device according to any one of claims 1 to 6, wherein the image generator performs antialiasing on edges included in the captured image to generate the projection image. The lighting device according to any one of claims 1 to 7,
a head incorporating the imaging unit and the projector;
and a stand portion that supports the head,
An imaging unit captures an image of a range in which the visual object can be placed, which is a predetermined range on a plane on which the stand unit is placed, and for the visual target placed in the predetermined range, A lighting device that superimposes the generated projection image by the projector. The lighting device according to any one of claims 1 to 8,
comprising a visible position specifying unit that specifies a position on a visual target visually recognized by a user;
The image generation unit generates the projection image from the captured image of the identified position on the visual target. An illumination method for illuminating a visual object, comprising:
imaging a visual object;
storing in advance a clear vision model that reflects the relationship between the easiness of recognition of a visual object including characters and at least the brightness and contrast of the characters that are the visual objects;
At least the brightness and contrast of characters, which are the visual target, are recognized from the captured image of the visual target, and the clear vision model is used to set the clarity of the visual target within a desired range. generate the projection image from
An illumination method, wherein the projection image is superimposed on the visual target by projecting the projection image onto the visual target using a projector. A first lighting device, which is the lighting device according to any one of claims 1 to 8, and a second lighting device, which is provided separately from the first lighting device and uses a projector to illuminate a predetermined range. A lighting system comprising a lighting device,
The second lighting device,
illuminating a range different from the range illuminated by the first illumination device and wider than the illumination range of the first illumination device;
analyzing an illumination range image obtained by imaging the illumination range, generating an edge-enhanced image that emphasizes edges of the illumination range image, projecting the edge-enhanced image by the projector of the second illumination device; An illumination system that superimposes the edge-enhanced image on an illumination area.

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