Due to the complexity of color vision, color measurement and visual evaluation conditions must be standardized so that the results are comparable. According to the International Commission on Illumination CIE, color measurement must be standardized in three areas:
1 When calculating the tristimulus value of the sample to be measured, the illumination source selects the standard illuminator. The commonly used standard illuminators are A, C, and D65. 2 When calculating the tristimulus value of the sample to be measured, the standard observer, small field of view is used. (1°~4°) select CIE1931 standard chromatic observer, select CIE1964 standard complementary chromatic observer for large field of view (10°); 3 measurement device must select standardized geometry (Geometry), ie standard illumination observation condition .
Three elements of color vision
Color measuring equipment and visual evaluation
This issue is based on the theme of lighting observation geometry.
CIE recommended geometric conditions before 2004
The color measurement of the object color is achieved by measuring the spectral or tristimulus values, so the measurement results are related to the relative positional relationship of the light source, detector and sample, ie the geometric conditions. Similarly, the visual evaluation of color samples is also affected by the geometry of the illumination and observation. The degree of correlation between the measurement results and the visual evaluation depends on the degree of simulation of the geometric conditions of the instrument under actual observation. Prior to 2004, the CIE specified four geometric conditions for reflection measurements and four transmission measurement geometries based on the main way in which objects were observed by the human eye. Taking reflection measurement as an example, as shown in the figure below, these geometric conditions include: 0/d (vertical illumination/diffuse reception), d/0 (diffuse illumination/vertical reception), 0/45 (vertical illumination/45° reception) ) and 45/0 (45° illumination / vertical reception).
CIE's four reflection measurement geometries before 2004
According to the CIE regulations, the spectral reflection factors measured under the three conditions of 0/45, 45/0, d/0 are called spectral radiance factors, which are respectively recorded as Ï0/45, Ï45/0, Ïd/0; at 0/ The spectral reflectance measured under the condition d is called the spectral reflectance Ï.
CIE recommended geometric conditions in 2004
With the continuous development of instrument manufacturing and other color applications, geometric conditions are implemented in a variety of ways, and the above-mentioned representation of geometric conditions can not fully explain the measurement state. For example, whether or not the regular reflection component or the specular reflection component is included, the implementation of incident light in the 45/0 condition, etc., is not represented in the symbol. Therefore, CIE revised the representation of geometric conditions in its publications in 2004 and removed the reference to “illumination/observation conditions†in instrumental measurements, replacing them with “geometric conditions†to avoid visual observation. The conditions are confused.
For the measurement of object reflection chromaticity, CIE specifies the following 10 geometric conditions
(1) Diffuse: 8° geometry, including specular components; shorthand for di: 8°
Here, di is an abbreviation for Diffusion and Included. As shown in the figure below, the sampling aperture is uniformly illuminated from all directions by the inner surface of the hemisphere bounded by its plane, and the measurement area is overfilled. The detector responds uniformly to the sampling aperture region, the reflected beam axis is at an angle of 8° to the sample center normal, and the radiation reflected by the sampling aperture is considered uniform in all directions within 5° of the receiving beam axis.
CIE di: 8° geometry
(2) Diffuse: 8° geometry, excluding mirror components; the shorthand notation is de: 8°
Here, de is an abbreviation for Diffusion and Excluded. As shown in the figure below, the di:8° condition is first met, but a dih trap is substituted for the di:8° reflection plane. Therefore, when a single-sided planar mirror is placed at the sampling aperture, no light is reflected to the detector direction, and there is no specular reflection within 1° of this direction to leave latitude for the instrument stray light or alignment error.
CIE de: 8° geometry
(3) 8°: diffuse geometry, including specular components; shorthand notation 8°: di
This geometric condition satisfies the condition of di: 8°, but the illumination source is opposite to the optical path of the detector. Thus the sampling aperture is illuminated by light at an angle of 8° to the normal, and the flux of the various angles reflected by the sampling aperture is collected by the hemisphere bounded by the reference plane, as shown in the following figure.
CIE 8°: di geometry
(4) 8°: Diffuse geometry, excluding the mirror reflection component; the shorthand symbol is 8°: de
This geometry satisfies the condition of de: 8°, but the illumination source is opposite to the detector's optical path, as shown in the following figure.
8°:de geometry of CIE
(5) Diffuse/diffuse geometry, abbreviated as d:d
The illumination of this geometric condition satisfies the condition of di: 8°, and the hemispheres bounded by the reference plane collect the respective angular fluxes of the sampling aperture reflection.
(6) Alternative diffusing geometry conditions (d: 0°)
This geometric condition is an alternative diffusing geometry condition whose exit direction is along the sample normal, which is a strict geometric condition that does not include specular reflection.
(7) 45° belt/vertical geometry (45°a: 0°)
Here, a is an abbreviation for annular. As shown in the figure below, the apex is located at the center of the sampling aperture, the central axis is located on the normal axis of the sampling aperture, and the light emitted from each direction between the two positive cones with half angles of 40° and 50° uniformly illuminates the sampling aperture; The reflected radiation is uniformly received from the apex at the center of the sampling aperture, and the central axis is uniformly distributed in a positive cone with a half angle of 5° along the normal direction of the sample. This geometry minimizes the effects of selective reflection of sample texture and orientation. If such illumination geometry is approximated by a plurality of light sources arranged in close proximity to the shape, or by a plurality of light exits arranged in a circular shape and approximated by a single source, a circumferential/vertical geometry condition is obtained (45). °c: 0°).
45°a: 0° geometry specified by CIE
(8) Vertical/45° band geometry (0°: 45°a)
The angle and space conditions satisfy the condition of 45°a:0°, but the illumination source is opposite to the optical path of the detector. Thus the sampling aperture is illuminated vertically and the reflected radiation is received by an annulus at a 45° angle from the center to the normal.
(9) 45° single orientation / vertical (45° x: 0°)
The angular and spatial conditions satisfy the condition of 45°a: 0°, but the radiation is emitted from only one azimuth, which excludes specular reflection, but highlights texture and directionality. The symbol x indicates that the incident beam illuminates the reference plane from any arbitrary orientation.
(10) Vertical 45° single orientation (0°: 45° x)
The angle and space conditions satisfy the condition of 45° x: 0°, but the optical path is reversed. The surface of the sample is thus illuminated vertically, receiving reflected radiation from a certain angle at a 45° angle to the normal.
The CIE stipulates that the measurement result in the case of geometric conditions conforming to (1), (2), (6), (7), (8), (9), (10) is the spectral reflection factor; when the measurement angle is sufficient In hours, the magnitude of the reflection factor is the same as the magnitude of the radiance factor. When the geometric condition (3) is met and the integrating sphere is the ideal integrating sphere, the measurement result is the reflectance, which is also the most commonly used geometrical condition of the benchtop spectrophotometer. Therefore, the radiance factor β45:0 can be given under the condition of 45°×:0°; the radiance factor β0:45 can be given under the condition of 0°:45°×; the radiance can be given under the condition of di:8° The factor βdi: 8, which is close to the radiance factor βd: 0; the measurement at 8°: di is the reflectance Ï.
For color measurement of transmissive objects, CIE specifies the following six geometric conditions.
(1) Vertical/vertical geometry (0°: 0°)
As shown in the figure below, the geometry of the incident and measurement are exactly the same as the conical shape. The axis of the cone is located on the normal line at the center of the sampling aperture, the half angle is 5°, the surface and angular radiation of the sampling aperture and the surface response of the detector And the angle response is uniform.
CIE transmission measurement 0°: 0° geometry
(2) Diffuse/vertical geometry, including rule components (di: 0°)
As shown in the figure below, the sampling aperture is uniformly illuminated from all directions by the hemisphere bounded by the first reference plane, and the measuring beam is the same as the 0°:0° geometry.
CIE transmission measurement di: 0° geometry
(3) Diffuse/vertical geometry, rule out rule components (de: 0°)
This geometry satisfies di:0°, but when the sampling aperture is open (eg, no sample is placed), the center of the sampling aperture is measured, there is no light directly to the detector, and there is no direct light within 1°.
(4) Vertical/diffuse geometry, including regular components (0°: di)
This geometry is opposite to di:0°, as shown in the following figure.
0°:di geometry for transmission measurement of CIE
(5) Vertical/diffuse geometry, rule out rule components (0°: de)
The position of the source and detector of this geometry is opposite to de:0°.
(6) Diffuse/diffuse geometry (d:d)
The sampling aperture of the geometric condition is uniformly illuminated from the respective angles by the hemisphere bounded by the first reference plane, and the transmission flux is uniformly received from the respective angles by the hemisphere bounded by the second reference plane, as shown in the following figure.
d:d geometry of transmission measurement of CIE
According to the CIE, in the above measurement geometry, the amount measured under the rule of exclusion is the transmission factor, and the rest are the transmittance.
Push Button Switches
The Push Button Switches, also known as the control button (referred to as the button), is a low-voltage electrical appliance that is manually and generally can be automatically reset. The Push Button Starter Switch is usually used to issue a start or stop command in the circuit to control the turning on and off of electrical coil currents such as electromagnetic starters, connectors, and relays.
The On Off Push Button Switches refers to a switch that pushes the transmission mechanism with a button to make the movable contact and the static contact open or close and realize circuit switching. It is a master control device with a simple structure and a wide range of applications. In the electrical automatic control circuit, used to manually send control signals to control connectors, relays, electromagnetic starters, etc.
This Pushbutton Switches is a kind of electric device that is used to switch on and off the small current circuit when the action is released. Generally used in AC and DC voltage below 440V, the current is less than 5A in the control circuit, generally do not directly manipulate the main circuit can also be used in the interconnection circuit. In actual use, in order to prevent desperation, different marks are usually made on the buttons or painted with different colors, and the colors are red, yellow, blue, white, black, green, and the like.
The Momentary Push Button Switch could be divided into metal push button switches and LED Light Switches and ordinary snap button type, mushroom head type, self-locking type, self-resetting type, rotary handle type, with indicator light type, lighted symbol type and key type, etc., with single button and double Buttons. Generally, it adopts a water-storage structure, which consists of a button cap, a return spring, a static contact, a moving contact and a casing. It is usually made into a composite type, and has a pair of normally closed contacts and normally open contacts, and some products can pass. The series connection of multiple elements increases the number of contact pairs. There is also a self-contained button that automatically holds the closed position when pressed, and can be turned on only after the power is turned off.
When the Metal Switches is not pressed, the movable contact is connected with the upper stationary contact. The pair of contacts is called a normally closed contact. At this point, the movable contact is disconnected from the following static contact. The pair of contacts is called a normally open contact: the button is pressed, the normally closed contact is open, the normally open contact is closed, and the button is released. Restore the original working state under the action of the return spring
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