CN112903136A - Temperature indicating device - Google Patents
Temperature indicating device Download PDFInfo
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- CN112903136A CN112903136A CN202010990019.0A CN202010990019A CN112903136A CN 112903136 A CN112903136 A CN 112903136A CN 202010990019 A CN202010990019 A CN 202010990019A CN 112903136 A CN112903136 A CN 112903136A
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- liquid crystal
- cholesteric liquid
- light
- temperature
- cylindrical mirror
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/12—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in colour, translucency or reflectance
- G01K11/16—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in colour, translucency or reflectance of organic materials
- G01K11/165—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in colour, translucency or reflectance of organic materials of organic liquid crystals
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- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Liquid Crystal (AREA)
Abstract
The invention discloses a temperature indicating device, which relates to the field of temperature sensing and comprises a light source, a cylindrical mirror, a cholesteric liquid crystal waveguide element, a beam expander and a receiving screen. The light source is a white light source; the cylindrical mirror is a convex cylindrical mirror and has coupling and adjusting functions on light beams; the cholesteric liquid crystal waveguide element is sequentially provided with a substrate, a cholesteric liquid crystal layer, a glass plate, a cholesteric liquid crystal layer and a substrate from top to bottom. The refractive index of the cholesteric liquid crystal layer is larger than that of the glass plate; the beam expander consists of two convex lenses and is used for adjusting emergent light passing through the waveguide into parallel light; the receiving screen is a white screen, and the change of the color of the emergent light spot is displayed better. The invention is based on the waveguide structure of cholesteric liquid crystal Bragg reflection, and the temperature is directly displayed according to the color change of the emergent light spot of the cholesteric liquid crystal waveguide element, so that the invention is simple and clear. The device is reliable in work, can realize remote temperature indication, can be manufactured into an instrument working indicator lamp with a temperature indication function, and is low in cost.
Description
Technical Field
The invention relates to the field of temperature sensing, in particular to a cholesteric liquid crystal temperature sensor.
Background
With the research on the technical fields of liquid crystal and sensing, the liquid crystal sensor is widely applied to social production and life, and certainly, the liquid crystal temperature sensor is not lacked. In various types of liquid crystals, cholesteric phaseLiquid crystals are one of the most attractive liquid crystals due to their unique optical properties. The most common cholesteric liquid crystal temperature sensor utilizes its thermochromatic effect, i.e. when the visible wavelength satisfies the Bragg reflection condition
Then, one will observe the color of the corresponding wavelength, and as the temperature changes, the pitch changes, thereby producing a color change. The cholesteric liquid crystal temperature sensor in the prior art is mostly complex in structure and high in cost; or the method is simple but inconvenient to observe, has low reuse rate and can not well detect the ambient temperature.
Disclosure of Invention
The invention provides a waveguide structure based on cholesteric liquid crystal Bragg reflection, and a device for indicating temperature by using color change of emergent light spots, aiming at the defects that the conventional cholesteric liquid crystal temperature sensor is inconvenient to observe and cannot well detect the ambient temperature and the like, so as to solve the problems.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a temperature indicating device comprises a light source, a cylindrical mirror, a cholesteric liquid crystal waveguide element, a beam expanding mirror and a receiving screen.
The light source is a white light source, and interference of incident light color on emergent light color when the cholesteric liquid crystal pitch generates selective reflection along with temperature change is prevented.
The cylindrical mirror is a convex cylindrical mirror. The cylindrical mirror couples the light beam into the glass plate of the cholesteric liquid crystal waveguide element.
The cholesteric liquid crystal waveguide element is sequentially provided with a substrate, a cholesteric liquid crystal layer, a glass plate, a cholesteric liquid crystal layer and a substrate from top to bottom. The refractive index of the two cholesteric liquid crystal layers is larger than that of the glass plate.
The beam expander consists of two convex lenses. The first convex lens firstly converges emergent light, and then the emergent light is adjusted by the second convex lens to form parallel light beams.
The receiving screen is a white screen, and the change of the color of the emergent light spot is displayed better.
The invention has the beneficial effects that: the whole device is placed in a tested environment, and the temperature is displayed according to the color change of the emergent light spot of the cholesteric liquid crystal waveguide element, so that the device is simple, clear and visual. In the cholesteric liquid crystal waveguide element, an optical waveguide with a specific wavelength is formed in the middle glass layer due to Bragg reflection of liquid crystal, and the refractive indexes of the upper and lower layers of cholesteric liquid crystal are larger than that of the middle glass plate, so that only light with the corresponding Bragg reflection wavelength can be transmitted in the glass plate, and light with the other wavelengths is refracted out. Along with the change of the temperature, the central wavelength of the Bragg reflection changes correspondingly, so that the color of the emergent light wave changes according to the Bragg reflection. Thus, the temperature can be detected by emitting a light beam at one side of the cholesteric liquid crystal waveguide element, coupling the light into the glass plate, and observing the color of the received emergent light at the other side. The device principle is simple and clear, and reliable operation can realize remote temperature indicating, can also make the instrument and equipment work pilot lamp that takes the temperature indicating function according to this principle to the cost is very low.
Drawings
FIG. 1 shows absorption spectra of cholesteric liquid crystal at 30 deg.C, 35 deg.C, and 40 deg.C
FIG. 2 is a schematic structural diagram of the present invention
FIG. 3 is a schematic view of a cholesteric liquid crystal waveguide device
FIG. 4 is a schematic representation of the propagation of light waves of a particular wavelength in a glass plate with Bragg reflection
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
As shown in FIG. 1, at different temperatures, the cholesteric liquid crystal generates Bragg reflection with selective wavelength, and the average value of the reflection center wavelength and the cholesteric liquid crystal birefringence
Relation with pitch P of cholesteric liquid crystal
In the cholesteric temperature range, the helical structure is very sensitive to temperature. When the temperature changes, the pitch of the cholesteric liquid crystal also changes, resulting in a change in the central wavelength of the selective reflection.
As shown in fig. 2, the temperature indicating device comprises a light source 1, a cylindrical mirror 2, a cholesteric liquid crystal waveguide element 3, a beam expander 4 and a receiving screen 5. The cholesteric liquid crystal waveguide element 3 (fig. 2) includes a substrate 6, a cholesteric liquid crystal layer 7, a glass plate 8, a cholesteric liquid crystal layer 9, and a substrate 10 in this order from top to bottom. The light source is a white light source; the receiving screen is a white screen; the cylindrical mirror is a convex cylindrical mirror; the refractive index of the glass plate is smaller than the refractive indices of the cholesteric liquid crystal layer 7 and the cholesteric liquid crystal layer 9.
The specific working flow of the device is as follows:
the method comprises the following steps: construction of light paths
And placing the light source, the cylindrical mirror, the cholesteric liquid crystal waveguide element, the beam expander and the receiving screen in the order in the environment to be measured, and adjusting the central positions of the light source, the cylindrical mirror, the cholesteric liquid crystal waveguide element, the beam expander and the receiving screen to be at the same height.
When the cylindrical mirror is placed, the cylindrical mirror is adjusted to couple light into the waveguide element.
When the beam expander is placed, the beam expander is adjusted, so that light emergent after passing through the beam expander is parallel light beams.
Step two: other light sources of the environment where the device is located are turned off, and the measured result is prevented from being interfered.
Step three: and turning on a light source of the device to irradiate the cylindrical mirror, and adjusting the height of the cylindrical mirror and the distance between the cylindrical mirror and the light source and between the cylindrical mirror and the cholesteric liquid crystal waveguide structure to ensure that light is coupled into a glass plate in the cholesteric liquid crystal waveguide element.
Fig. 4 is a schematic diagram of the formation of a specific wavelength waveguide by light waves in a glass plate of a cholesteric liquid crystal waveguide element.
Step four: and adjusting the beam expander to enable the finally emergent light beams to be parallel as much as possible.
Step five: the height of the receiving screen and the distance between the receiving screen and the beam expander are adjusted, so that emergent light can be clearly presented on the receiving screen.
In summary, the above description uses preferred embodiments to illustrate the invention in detail, not to limit the scope of the invention. After reading this disclosure, those skilled in the art will make minor changes and modifications to the invention without departing from the spirit and scope of the invention.
Claims (8)
1. A temperature indicating device is characterized by comprising a light source, a cylindrical mirror, a cholesteric liquid crystal waveguide element, a beam expander and a receiving screen,
the cholesteric liquid crystal waveguide element comprises an upper substrate, a lower substrate, two cholesteric liquid crystal layers and a glass plate.
The beam expander comprises two convex lenses.
2. A temperature display device according to claim 1, wherein the light source is white light.
3. A temperature indicating device according to claim 1, wherein a cholesteric liquid crystal doped with a temperature sensitive chiral agent is used, the pitch of which varies with temperature when visible light is incident and is satisfied
Then, a strong selective reflection is produced.
4. A temperature display device according to claim 1, wherein the refractive index of the upper and lower cholesteric liquid crystal layers of the glass sheet is greater than the refractive index of the glass sheet, such that only light of the wavelength corresponding to the bragg reflection is transmitted through the glass sheet and light of the remaining wavelengths is refracted away.
5. A temperature indicating device according to claim 1, wherein the pitch of the cholesteric liquid crystal varies with temperature as the average of the birefringence of the cholesteric liquid crystal at the reflection wavelength
And the pitch P of the cholesteric liquid crystal
Then, bragg reflection occurs, and light of a specific wavelength propagates through the glass plate.
6. A temperature display apparatus according to claim 1, wherein the cylindrical mirror is a convex cylindrical mirror for coupling and adjusting the light beam.
7. A temperature indicating device according to claim 1, wherein the beam expander comprises two convex lenses for converging and diverging the light respectively, and adjusting the light beam so that the light projected onto the receiving screen is collimated.
8. A temperature indicating device according to claim 1, wherein the receiving screen is a white screen, and the temperature to be measured can be indicated according to the color of the light spot on the white screen due to the difference in temperature and the difference in wavelength of the emergent light.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010990019.0A CN112903136A (en) | 2020-09-21 | 2020-09-21 | Temperature indicating device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010990019.0A CN112903136A (en) | 2020-09-21 | 2020-09-21 | Temperature indicating device |
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| Publication Number | Publication Date |
|---|---|
| CN112903136A true CN112903136A (en) | 2021-06-04 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010990019.0A Pending CN112903136A (en) | 2020-09-21 | 2020-09-21 | Temperature indicating device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114721166A (en) * | 2022-04-26 | 2022-07-08 | 东南大学 | Contact lens containing thermochromic cholesteric liquid crystal material and preparation method thereof |
Citations (10)
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|---|---|---|---|---|
| GB1549584A (en) * | 1978-03-02 | 1979-08-08 | Standard Telephones Cables Ltd | Temperature responsive device |
| GB2083244A (en) * | 1980-08-27 | 1982-03-17 | Mcdonnell Damien Gerard | Temperature-sensitive cat's eyes |
| US4410283A (en) * | 1980-08-29 | 1983-10-18 | Thomson-Csf | Cholesteric liquid crystal of the reentrant type and a temperature-detecting device entailing the use of a liquid crystal of this type |
| US4469452A (en) * | 1982-04-14 | 1984-09-04 | Whitman Medical Corporation | Indicator system and means for irreversibly recording a temperature limit |
| CN101788346A (en) * | 2010-03-29 | 2010-07-28 | 温州大学 | High voltage electrical apparatus temperature detecting probe and high voltage electrical apparatus temperature monitoring system |
| CN207264069U (en) * | 2017-07-28 | 2018-04-20 | 广西天山电子股份有限公司 | A kind of cholesteric liquid crystal device and beam control system |
| CN109141670A (en) * | 2017-06-27 | 2019-01-04 | 江苏和成显示科技有限公司 | A kind of excess temperature monitoring device |
| CN110440948A (en) * | 2019-08-29 | 2019-11-12 | 深圳市德安里科技有限公司 | A kind of polymer dispersed liquid crystals heat-sensitive light modulation temperature card and its manufacturing method |
| CN111308821A (en) * | 2020-04-10 | 2020-06-19 | 合肥工业大学 | Liquid crystal sensing device and preparation method thereof |
| CN112730271A (en) * | 2020-12-15 | 2021-04-30 | 哈尔滨工程大学 | Liquid crystal optical fiber sensor for detecting VOC gas concentration and temperature and preparation method thereof |
-
2020
- 2020-09-21 CN CN202010990019.0A patent/CN112903136A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1549584A (en) * | 1978-03-02 | 1979-08-08 | Standard Telephones Cables Ltd | Temperature responsive device |
| GB2083244A (en) * | 1980-08-27 | 1982-03-17 | Mcdonnell Damien Gerard | Temperature-sensitive cat's eyes |
| US4410283A (en) * | 1980-08-29 | 1983-10-18 | Thomson-Csf | Cholesteric liquid crystal of the reentrant type and a temperature-detecting device entailing the use of a liquid crystal of this type |
| US4469452A (en) * | 1982-04-14 | 1984-09-04 | Whitman Medical Corporation | Indicator system and means for irreversibly recording a temperature limit |
| CN101788346A (en) * | 2010-03-29 | 2010-07-28 | 温州大学 | High voltage electrical apparatus temperature detecting probe and high voltage electrical apparatus temperature monitoring system |
| CN109141670A (en) * | 2017-06-27 | 2019-01-04 | 江苏和成显示科技有限公司 | A kind of excess temperature monitoring device |
| CN207264069U (en) * | 2017-07-28 | 2018-04-20 | 广西天山电子股份有限公司 | A kind of cholesteric liquid crystal device and beam control system |
| CN110440948A (en) * | 2019-08-29 | 2019-11-12 | 深圳市德安里科技有限公司 | A kind of polymer dispersed liquid crystals heat-sensitive light modulation temperature card and its manufacturing method |
| CN111308821A (en) * | 2020-04-10 | 2020-06-19 | 合肥工业大学 | Liquid crystal sensing device and preparation method thereof |
| CN112730271A (en) * | 2020-12-15 | 2021-04-30 | 哈尔滨工程大学 | Liquid crystal optical fiber sensor for detecting VOC gas concentration and temperature and preparation method thereof |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114721166A (en) * | 2022-04-26 | 2022-07-08 | 东南大学 | Contact lens containing thermochromic cholesteric liquid crystal material and preparation method thereof |
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Application publication date: 20210604 |