RU2552011C2 - Device for colour pattern building in intended direction of colour space - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medical equipment. A device for colour pattern building in an intended direction of a colour space comprises optical channels with standard and test colour stimuli shaping units, an assembly for the colour stimuli timing in a visual field of a person being tested; the device also comprises red, green and blue light sources mounted behind each of the screens. The test colour stimulus shaping unit comprises a source pulse ratio regulator, outputs of which are connected to control inputs of a test field PWM modulator, whereas inputs of the regulator are connected to outputs of m and n pulse ratio calculator; the outputs of the ratio calculator are connected to controllers of chromaticity coordinates x₁, y₁, x₂, y₂, x₃, y₃ and a direction angle α of the generated light.

EFFECT: using the presented device is expected to improve diagnostic accuracy in various forms of colour-blindness, to increase the quantity of generated colours and accuracy in reproduction.

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Description

A device for generating a color sample in a given color space direction belongs to the field of medicine, to the ophthalmology section and can be used for qualitative diagnostics of both congenital and acquired color vision deviations, for detecting color vision deviations in pilots, as well as for checking color perception of drivers of vehicles. The invention is aimed at increasing the accuracy of diagnosis when determining minor deviations in color vision.

As an analogue, the MacAdam polarization colorimeter [1], including Fresnel prisms, can be considered; interchangeable color filters; separating diaphragm; the prism of Wollaston; black trap; rochon prisms; biprisms; pupil exit device; photometric ball; filters for tinting the background.

The device is a kind of dual polarization photometer with a common Wollaston prism (polarizer) and with two rotating Rochon prisms (analyzers) equipped with limbs with measuring scales.

A feature of the device lies in the method of forming the input beams of photometers. Two light beams I and II coming into the device from a common source (not shown in the figure) are each separated in the vertical direction by two Fresnel prisms P ₁ and P ₂ into two beams. In the upper beam is placed a filter Ф _{1 of} one color, in the lower one - a filter Ф _{2 of} another color. Between the prisms and the filters are lenses that respectively collect all the beams on the Wollaston B prism. After exiting the Wollaston prism, they follow along the optical axis of the device polarized in two mutually perpendicular directions, i.e. an ordinary ray of one color and an unusual ray of another color enter the corresponding Rochon prisms P ₁ and P ₂ . The remaining pairs of polarized rays are absorbed by black traps.

After passing through Rochon prisms, the rotation angles of which fix various mixtures of two colors, the light beams are reduced by biprisms and lenses into the pupil of the device exit. The observer sees the field of view, divided by a vertical border into two equal halves. The color of each half is formed by mixing colors in bundles I and II, respectively.

The eyepiece is surrounded by a photometric ball Ш whitened inside, with a corresponding shade, which can be changed at will by the choice of light filters f.

With the known characteristics of the filters Ф ₁ and Ф _{2, the} color of each of the fields of comparison of the device is determined by the formulas:

и $${\overline{x}}_2,{\overline{y}}_2,{\overline{z}}_2$$

$$$$

- координаты цветов светофильтров,Where $${\overline{x}}_{\mathrm{one}},{\overline{y}}_{\mathrm{one}},{\overline{z}}_{\mathrm{one}}$$

and $${\overline{x}}_2,{\overline{y}}_2,{\overline{z}}_2$$

$$$$

- the coordinates of the colors of the filters,

θ is the angle of rotation of the analyzer prism.

Different values of the parameter θ characterize all colors that lie on a straight line connecting the colors of the filters Ф ₁ and Ф ₂ . Having fixed one of the values of the angle θ on both Rochon prisms, it is possible, violating and restoring color equality by turning one of the Rochon prisms, to determine the spread of the measurement error in this direction and, equally, the color discrimination thresholds.

, т.е. светлоты.A set of hundreds of filters of a wide variety of colors with different coordinate values is attached to the device. $$\overline{y}$$

, i.e. lightness.

The main disadvantage of the polarization colorimeter is the complex optical design, which requires the selection of filters for each individual measurement, in addition, due to such a design feature, information about the third color coordinate is lost during measurements.

Closest to the technical nature of the present invention is a visual colorimeter [2], which allows to synthesize radiation in a given direction of the color space.

The visual colorimeter for measuring the color characteristics of objects contains: low-inertia sources of red 4, green 5 and blue 6 radiation from a system for the formation of two fields of view of the measured and synthesized colors and a system for adjusting the color ratio, characterized in that the ratio of the primary colors changes in such a way that the pulse generator 11 generates pulses with a frequency ƒ = 1 / t, and its output is connected to the triggering inputs of the duty cycle regulators 12, while simultaneously with the leading edge I start of the impulse at the output of the duty cycle regulators 12, a potential appears that enters the outputs of the stabilizers 9 of the radiation power of the radiation sources 4-6.

The visual colorimeter works as follows. The image of the object using the lens 1 is projected in a plane passing through the photometric cube 2 and dividing the left and right fields of view in half. With the help of an eyepiece 3, both fields of view - measuring and comparative - are examined simultaneously by the observer.

Sources of radiation 4-6, which together with the filters 7 form the primary colors, are mixed with the help of mirrors 8 in the comparative field of view of the photometric cube 2.

Low-inertia radiation sources operate in a pulsed mode with a switching frequency greater than critical, so that the observer ceases to notice flicker and perceives the radiation as continuous.

For the used brightness levels, the critical frequency lies in the range of 40–50 Hz.

Depending on the position of the adjusters 13 connected to the control inputs of the duty cycle regulators 12, the corresponding pulse duration t _u , and therefore the duty cycle of the pulses, is set. The radiation power stabilizers 9 have a negative feedback on the radiation power that is formed by the photodetectors 10 associated with the respective radiation sources. At the same time, at the output of the power stabilizers, such an amplitude of rectangular voltage pulses is maintained that ensures a constant emission power of the sources.

The disadvantage of the prototype is that it implements an outdated version of the construction, based on the analog method of radiation control, and the device is not intended to diagnose color vision.

The task of the invention is to improve the accuracy of diagnosis of various forms of color perception disorders, increase the number of synthesized colors and the accuracy of their reproduction.

The technical result from the solution of the problem lies in the fact that in the device for generating a color sample in a given direction of the color space containing optical channels with blocks for generating reference and test color stimuli, a node for combining color stimuli in the subject’s field of view, sources of red, green and blue radiation located behind each of the screens, and a regulator of the ratio of the duty cycle of the pulses of radiation sources, the outputs of which They are connected to the control inputs of the PWM modulator of the test field, and the controller inputs are connected to the outputs of the pulse ratio calculator m and n, and the inputs of the ratio calculator are connected to color coordinators x1, y1, x2, у2; x3, y3 and the direction angle α of the synthesized radiation, while the ratio of the duty cycle of the pulses of the radiation sources are set by the regulator.

In FIG. 1 is a functional diagram of a device for forming a color sample in a given direction of the color space, which shows:

1 - matte screen;

2 - an opaque partition;

3 - signal amplifier;

4, 5, 6 - spectrozonal radiation sources;

7 - pulse-width modulators (PWM);

8 - pulse duty cycle regulator;

9 - calculators of the ratio of the duty cycle of pulses;

10 - color coordinate adjusters;

11 - color coordinate adjusters;

12 - adjuster of the direction of the angle of color synthesis.

In FIG. 2 is a graphical explanation of the synthesis of color in a given direction, which shows:

x1, y1; x2, y2; x3, y3 - color coordinates of the radiation of red, green and blue emitters;

xp1, yp1; xp2, ur2 - color coordinates of the points between which the color synthesis line passes;

α is the angle of the direction of color synthesis;

x, y are the chromaticity coordinates of the synthesized color.

In FIG. Figure 3 shows the optical design of the McAdam colorimeter (analog), which shows:

I and II - beams of light;

P ₁ and P ₂ - Fresnel prisms;

F ₁ - filter of the same color;

F ₂ - a filter of a different color;

D - separating diaphragm;

In - a prism of Wollaston;

H - black trap;

P ₁ and P ₂ are Rochon prisms;

O - eyepiece;

Ш - photometric ball;

f is the choice of filters.

In FIG. 4 shows a functional diagram of a visual colorimeter (prototype), which shows:

1 - lens;

2 - photometric cube;

3 - eyepiece;

4, 5, 6 - radiation sources;

7 - light filters;

8 - mirrors;

9 - power stabilizers;

10 - photodetectors;

11 - pulse generator;

12 - duty cycle controller;

13 - duty cycle adjusters.

The device for generating a color sample in a given direction of the color space consists of two transparent matte screens 1. Behind two transparent matte screens separated by an opaque partition 2, there are two triads of red 4, green 5, blue 6 radiation sources. The luminous flux from one triad of radiation sources evenly illuminates the left screen, and from the second triad the right screen. The radiation sources through amplifiers 3 are connected to three-channel 12-bit PWM modulators 7. The PWM modulator of the reference channel is connected to the duty cycle calculator 9. Data on the color coordinate necessary for synthesis is set by the color coordinate adjuster 10 connected to the duty ratio calculator. In the PWM test channel, the modulator is connected to the regulator of the ratio of the duty cycle of the pulses 8. The calculator of the ratio of the duty cycle 9 is connected to the adjusters of the coordinates of the color 11 and the adjuster of the direction of the angle of synthesis 12 and is connected to the regulator of the duty cycle of the pulses.

The task of improving the accuracy of diagnosing color vision can be solved by applying the proposed constructive solution when color synthesis is carried out over the entire area of the color space by pulse-width modulation of radiation.

In the reference channel, using the color coordinate adjuster, the color coordinates are set, the data of which are sent to the duty ratio calculator 6. The relations obtained according to formulas (1) and (2) are transmitted to the PWM modulator via the I2C data bus in the form of a digital code that generates the necessary signal to obtain the desired radiation sources:

where N _to , N _s , N _c - fill factors of the radiation pulses of red, green, blue radiation sources;

xk, yk, zk; xs, knots, zz, xs, whiskers, zc - color coordinates of the radiation of red, green and blue radiation sources;

C _xi C _yi C _zi - proportionality coefficients connecting color coordinates with corresponding color coordinates.

The direction of synthesis is given by the line between the points with the chromaticity coordinates, which are determined by the following expressions:

where xp1, yp1; xp2, ur2 - the coordinates of the color of the points between which passes a line that sets the direction of color synthesis;

x1, y1; x2, y2; x3, y3 - color coordinates of the radiation of red, green and blue emitters;

α is the angle of the direction of color synthesis;

x, y are the chromaticity coordinates of the synthesized color.

In the test channel, the chromaticity coordinates and the angle of synthesis are initially set, the data on which from the calculator of the ratio of the duty cycle is supplied to the PWM modulator. Thus, the direction of color synthesis in the color space is set. Between the duty ratio calculator and the PWM modulator, a three-channel duty ratio ratio regulator is included, which allows you to control the radiation of each radiation source. Due to this, it becomes possible to change the color of the radiation and equalize the two color fields formed on the matte screen. Having passed the PWM modulator, the signals go to the signal amplifier, the outputs of which are connected to the contacts of the radiation sources. The received signal ignites three colors (red, blue, green) in a predetermined proportion, as a result of which the required color sample is formed on the screen by additive addition of three colors.

Information sources

1. MacAdam D.L., Visual sensitivities to color differences, // J. Opt. Soc. Am. http: //1943.vol.33p.18/;

2. Copyright certificate SU 1554554 / A1 for the invention “Visual colorimeter”, IPC G01J 3/46, published on 08/10/1987.

Claims (1)

A device for generating a color sample in a given direction of the color space, containing optical channels with blocks for generating reference and test color stimuli, a node for combining color stimuli in the subject’s field of vision, characterized in that the sources of red, green, and blue radiation are located behind each of the screens, and in a test color stimulus formation unit, a regulator of the ratio of the duty cycle of the pulses of radiation sources is introduced, the outputs of which are connected to the control inputs of the PWM modulator t Stow field, and the controller inputs are connected to outputs pulses the duty ratio calculator relationship m and n, and calculating the relationship inputs are connected with setpoint chromaticity coordinates x1, y1; x2, y2; x3, y3 and the direction angle α of the synthesized radiation, while the ratio of the duty cycle of the pulses of the radiation sources are set by the regulator in accordance with the dependencies:

where N _to , N _s , N _with - fill factors of the radiation pulses of red, green, blue sources;
xk, yk, zk; xs, knots, zz, xc, whiskers, zc - chromaticity coordinates of the radiation of red, green and blue radiation sources;
C _xi , C _yi , C _zi - proportionality coefficients connecting color coordinates with color coordinates X _i = N _i C _xi x _i , Y _i = N _i C _yi y _i , Z _i = N _i C _zi z _i;
and the direction of synthesis is given by the line between the points with the chromaticity coordinates, which are determined by the following expressions:

where xp1, yp1; xp2, ur2 - the coordinates of the color of the points between which passes a line that sets the direction of color synthesis;
x1, y1; x2, y2; x3, y3 - color coordinates of the radiation of red, green and blue emitters;
α is the angle of the direction of color synthesis;
x, y are the chromaticity coordinates of the synthesized color.

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