Liquid crystal writing device

Abstract

The utility model discloses a liquid crystal writing device, include: liquid crystal writing film, for bearing the substrate of liquid crystal writing film and main control unit, be equipped with first test area on the liquid crystal writing film, the position of corresponding first test area on the substrate is equipped with the opening, fixedly be equipped with the illumination sensor in the opening, the illumination sensor is opposite liquid crystal writing film setting, and the illumination sensor is connected with main control unit. The utility model does not need manual intervention, has greatly saved maintenance cost, has promoted the use experience of user.

Description

Technical Field

[0001] This utility model relates to the field of liquid crystal writing devices, and in particular to a liquid crystal writing device. Background Technology

[0002] The statements in this section are merely background information related to this utility model and do not necessarily constitute prior art.

[0003] Currently, liquid crystal writing devices on the market often work by recording the writing pressure trajectory of the pen through pressure applied to the liquid crystal writing board. By applying an electric field, the cholesteric liquid crystal structure changes, thereby causing the writing pressure trajectory to disappear and thus erasing the writing.

[0004] However, in practical applications, it has been found that the erasing voltage required by the liquid crystal may vary with one or more factors such as ambient temperature, liquid crystal layer thickness, and the degree of liquid crystal aging. Therefore, if a fixed erasing voltage is used, when the erasing voltage required by the liquid crystal is increased due to external factors, the actual erasing voltage may be too low, resulting in incomplete erasing. When the erasing voltage required by the liquid crystal is decreased due to external factors, the actual erasing voltage may be too high, causing the text in the surrounding non-erasable areas to fade or disappear.

[0005] Existing technology discloses the use of an additional temperature sensor to detect the ambient temperature and to match the required erasure voltage based on a pre-calibrated relationship between temperature and erasure voltage. However, this relationship is calibrated at the time of product manufacturing. As the LCD writing device is used for longer periods, its aging process also increases, which can affect the erasure voltage. Therefore, after prolonged use, this relationship becomes inaccurate, thereby reducing the accuracy and reliability of erasure voltage adjustment. Utility Model Content

[0006] To address the aforementioned issues, this invention proposes a liquid crystal writing device. An illuminance sensor is added to a designated area below the liquid crystal writing film to measure the illuminance value of the corresponding area. The illuminance value reflects the state of the liquid crystal under the current erasure voltage. When the illuminance value meets certain conditions, it indicates that the area can be completely erased under the current voltage, thus obtaining a suitable erasure voltage.

[0007] In some implementations, the following technical solutions are adopted: A liquid crystal writing device includes: a liquid crystal writing film, a substrate for supporting the liquid crystal writing film, and a main control unit; the liquid crystal writing film has a first test area, the substrate has an opening at a position corresponding to the first test area, an illuminance sensor is fixedly disposed in the opening, the illuminance sensor is positioned facing the liquid crystal writing film, and the illuminance sensor is connected to the main control unit.

[0008] In other embodiments, the following technical solutions are adopted: A liquid crystal writing device includes: a liquid crystal writing film, a substrate for supporting the liquid crystal writing film, and a main control unit; the liquid crystal writing film has a first test area, the substrate has an opening at a position corresponding to the first test area, an illuminance sensor is fixedly installed in the opening, the illuminance sensor is positioned facing the liquid crystal writing film, and the illuminance sensor is connected to the main control unit. It also includes a temperature sensor, which is connected to the main control unit.

[0009] The temperature sensor is disposed in an opening corresponding to the first test area, the second test area, the third test area, or the fourth test area; or, the temperature sensor is disposed in an opening at another position on the liquid crystal writing film between the liquid crystal writing film and the substrate; or, the temperature sensor is disposed in the frame of the liquid crystal writing device, and a through hole communicating with the outside is opened on the frame at the corresponding position.

[0010] As a further embodiment, the liquid crystal writing film includes a first conductive layer, a bistable liquid crystal layer, and a second conductive layer disposed sequentially; the first conductive layer and the second conductive layer are respectively divided into multiple mutually insulated and parallel conductive regions, and the conductive regions of the first conductive layer and the conductive regions of the second conductive layer are spatially perpendicular to each other.

[0011] As a further solution, a second test area is selected within the conductive area covering the first test area on the first conductive layer, wherein the second test area does not overlap with the first test area; An opening is provided on the substrate at the position corresponding to the second test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit. And / or, Within the conductive area covering the first test area on the second conductive layer, a third test area is selected, and the third test area does not overlap with the first test area. An opening is provided on the substrate at the position corresponding to the third test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit.

[0012] As a further solution, a fourth test area is selected on the first and second conductive layers, in addition to the conductive area of ​​the first test area. An opening is provided on the substrate corresponding to the fourth test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit.

[0013] As a further embodiment, the illuminance sensor is fixed on a circuit board, which is fixed on a substrate; the circuit board is connected to a wiring port, which is connected to the main control unit.

[0014] As a further embodiment, the illuminance sensor is fixed on a circuit board, the circuit board is fixed on a support, the support is connected to the substrate and extends into the opening; the circuit board is connected to a wiring port, which is connected to the main control unit; the support is provided with a wire outlet hole to lead out the wiring on the circuit board.

[0015] As a further embodiment, the illuminance sensor is a monochrome analog output illuminance sensor or a tricolor analog output illuminance sensor; The signal transmission line of the monochrome analog output illuminance sensor or the tricolor analog output illuminance sensor is led out through the terminal block, connected to the amplifier circuit, and then connected to the AD pin of the main control unit. Alternatively, the illuminance sensor is a three-color digital output illuminance sensor; the signal transmission line of the three-color digital output illuminance sensor is led out through the wiring port and connected to the SPI bus or I2C bus of the main control unit. Alternatively, the illuminance sensor may be a photoresistor.

[0016] As a further solution, the first test area is selected at the corner of the liquid crystal writing film.

[0017] Compared with the prior art, the beneficial effects of this utility model are: (1) The liquid crystal writing device of this utility model detects the illuminance value of the selected test area by adding an illuminance sensor, and reflects the current state of the liquid crystal by the illuminance value; by continuously increasing the voltage difference applied to the test area, the illuminance value is not only increased, but when the illuminance value of the test area is greater than the set value, it indicates that the liquid crystal corresponding to the test area is in the focal conic state (that is, complete erasure is achieved); thus, it can be determined at what voltage the test area of ​​the liquid crystal writing film can make the liquid crystal change from the planar state to the focal conic state, and the erasure voltage required by the liquid crystal writing film can be accurately obtained. The test results are not affected by factors such as the thickness of the liquid crystal layer, the ambient temperature or the degree of aging.

[0018] (2) The liquid crystal writing device of this utility model can realize automatic detection of illuminance value and adjustment of erasure voltage according to preset logic, without manual intervention, which greatly saves maintenance costs and improves the user experience.

[0019] Other features and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of this aspect. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the conductive layer segmentation of the liquid crystal writing film in an embodiment of this utility model; Figure 2This is a schematic diagram of the installation structure of the illuminance sensor in an embodiment of this utility model; Figure 3 This is a schematic diagram of another installation structure of the illuminance sensor in an embodiment of this utility model; Figure 4 This is a schematic diagram showing the selection of the second and third test areas in an embodiment of this utility model; Figure 5 This is a schematic diagram of the selection of the fourth test area in an embodiment of this utility model; Among them, 1. Illuminance sensor, 2. Circuit board, 3. Wiring port, 4. Substrate, 5. Liquid crystal writing film, 6. Support component. Detailed Implementation

[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] First, it should be noted that transmittance measures the ability of light to pass through a liquid crystal layer. When the liquid crystal is in a planar state, the least amount of light passes through the liquid crystal layer, and the corresponding transmittance is the lowest. When the liquid crystal is in a focal conic state, the most amount of light passes through the liquid crystal layer, and the corresponding transmittance is the highest.

[0024] Light transmittance is the ratio of the illuminance value below the liquid crystal writing film to the illuminance value above the liquid crystal film. Since it is difficult to fix an illuminance sensor above the liquid crystal film and it affects aesthetics, this invention uses relative transmittance to characterize the state of the liquid crystal; the relative transmittance is: ;in, The current illuminance value of the illuminance sensor below the test area. The illuminance values ​​are obtained by the illuminance sensor when the liquid crystal in the test area is in a planar state during the same period. This refers to the illuminance value measured by the illuminance sensor when the liquid crystal in the test area is in a focal conic state during the same period. When the relative transmittance is greater than a certain value, such as 0.9, it indicates that the liquid crystal in the test area is in a focal conic state; when the relative transmittance is less than a certain value, such as 0.1, it indicates that the liquid crystal in the test area is in a planar state.

[0025] This embodiment determines the conditions that the illuminance value needs to meet based on the concept of relative transmittance.

[0026] In addition, since the test process is relatively short, we assume that the incident light intensity of the liquid crystal writing film remains constant during the same period.

[0027] Example 1 In one or more embodiments, a liquid crystal writing device is disclosed, specifically including: a liquid crystal writing film, a substrate for carrying the liquid crystal writing film, and a main control unit; The liquid crystal writing film includes, from top to bottom, a first conductive layer, a bistable liquid crystal layer, and a second conductive layer; combined with Figure 1 The first conductive layer is divided into multiple parallel and insulated X-direction conductive regions, and the second conductive layer is divided into multiple parallel and insulated Y-direction conductive regions; the X-direction conductive regions and the Y-direction conductive regions are arranged perpendicularly to each other. Of course, the orientation of the conductive regions can be adjusted according to actual needs.

[0028] The liquid crystal writing film has a first test area, and the substrate has an opening at the position corresponding to the first test area. An illuminance sensor is fixed in the opening, and the illuminance sensor is positioned facing the liquid crystal writing film. The illuminance sensor is connected to the main control unit.

[0029] As a specific implementation method, the first test area should be selected from a location on the liquid crystal writing film that is not usually used, such as a corner, so as not to affect the normal use of the writing device when automatically measuring the erasure voltage.

[0030] Figure 2 A specific installation method for an illuminance sensor is given. The illuminance sensor 1 is fixed on the circuit board 2. The circuit board 2 is fixed on the back of the opening position of the substrate 4. The illuminance sensor enters the opening and faces the liquid crystal writing film 5. The circuit board is also connected to the wiring port 3. The illuminance sensor 11 is connected to the main control unit through the wiring port 3.

[0031] Figure 3 Another specific installation method for the illuminance sensor is given. The illuminance sensor (not shown in the figure) is set on the circuit board 2 (such as PCB). The circuit board 2 is fixed on the support 6. The support 6 is a raised structure. Both ends of the support are connected to the substrate 4, and the middle raised part extends into the opening of the substrate 4. The circuit board 2 is fixed to the raised part of the support 6. On the one hand, this makes the illuminance sensor closer to the back of the liquid crystal writing film. On the other hand, it also provides a certain support for the liquid crystal writing film, so as to avoid the opening position affecting the writing of the liquid crystal writing film.

[0032] In this embodiment, the illuminance sensor can be a monochrome analog output illuminance sensor or a tricolor analog output illuminance sensor, which is low in cost and fast in testing. The signal transmission line of the monochrome analog output illuminance sensor or the tricolor analog output illuminance sensor is led out through the terminal, connected to the amplifier circuit, and then connected to the AD pin of the main control unit.

[0033] In this embodiment, the illuminance sensor can also be a three-color digital output illuminance sensor. The signal transmission line of the three-color digital output illuminance sensor is led out through the wiring port and connected to the SPI bus or I2C bus of the main control unit.

[0034] In this embodiment, the illuminance sensor can also be a photoresistor, such as a visible light photoresistor. The signal transmission line of the photoresistor is led out through the terminal block and connected to the AD pin of the main control unit.

[0035] It should be noted that when a three-color analog output illuminance sensor or a three-color digital output illuminance sensor is selected, the illuminance value used by the main control unit is basically derived from the value of the sensor that has the same color as the reflection of the liquid crystal writing film.

[0036] It should also be noted that when using an analog sensor, the illuminance value corresponds to the magnitude of the voltage or current.

[0037] In this embodiment, the main control unit is connected to the voltage generation circuit and the liquid crystal driver chip respectively. The voltage generation circuit is connected to the liquid crystal driver chip, and each voltage output channel of the liquid crystal driver chip is connected to each conductive area on the first conductive layer or the second conductive layer.

[0038] The first conductive layer and the second conductive layer each correspond to a voltage generation circuit and a liquid crystal driver chip, respectively. Taking the first conductive layer as an example, the main control unit can control the voltage generation circuit to output the voltage required by the liquid crystal driver chip. After receiving the voltage, the liquid crystal driver chip can output the corresponding voltage to each conductive area on the first conductive layer; the second conductive layer follows the same process. As a specific example, the liquid crystal driver chip can be an STN liquid crystal driver chip or a VFD driver chip. These are the inherent structures and functions of liquid crystal writing devices, and therefore will not be described in detail.

[0039] It should be noted that in this embodiment, when the liquid crystal driver chip outputs voltage to each conductive region on the two conductive layers, the voltages always satisfy a pre-configured relationship; during voltage adjustment, only the voltage difference continuously increases, while the relationship between the voltages applied to each conductive region remains unchanged, and the main control unit controls according to preset logic. A specific voltage application method is given below as an example: A first voltage V11 is applied to the conductive region covering the first test area on the first conductive layer, and a second voltage V12 is applied to other conductive regions on the first conductive layer; a third voltage V13 is applied to the conductive region covering the first test area on the second conductive layer, and a fourth voltage V14 is applied to other conductive regions on the second conductive layer; wherein, taking the third voltage V13 as a reference voltage, the first voltage V11, the second voltage V12, and the fourth voltage V14 satisfy the following: ; .

[0040] The specific voltage application method is known from existing technology, and this embodiment does not make any improvements.

[0041] Based on the structure of the liquid crystal writing device in this embodiment, the illuminance value corresponding to the test area A can be obtained when the two conductive layers are loaded with different voltage differences in the test area A. By comparing these illuminance values ​​with the set threshold, it can be determined at what voltage the liquid crystal in the test area A can change from a planar state to a focal conic state, that is, the test area can be completely erased; thus, the erasure voltage required by the liquid crystal writing film can be accurately obtained.

[0042] In this embodiment, the main control unit detects the required erasure voltage according to a predetermined time period (e.g., every half hour or every day) or by receiving an external trigger command. The specific detection logic can be pre-configured in the main control unit. It should be noted that this embodiment is only an improvement on the device structure. The specific detection logic can be configured as needed. The function implemented by the main control unit in the whole process is to control the voltage generation circuit to output different voltages to the liquid crystal driver chip in a certain time sequence, and to determine the magnitude relationship of the illuminance values ​​detected by the illuminance sensor. These functions can be fully realized by the existing main control unit.

[0043] As a specific example, the specific working process of the device in this embodiment can be as follows: By applying voltage to put the liquid crystal in the first test area into display mode, the voltage difference applied to the first test area is controlled to change from small to large, and the illuminance value of the first test area is recorded for each voltage change. When the illuminance value is greater than or equal to the set threshold, it means that the first test area has been erased cleanly, and the corresponding voltage difference can be used as the erasure voltage of the current liquid crystal writing film.

[0044] The process of applying voltage to put the liquid crystal in the first test area into a display state is achievable using existing technology. A specific example is given below: The main control unit controls the voltage generation circuit to output a predetermined voltage to the liquid crystal driver chip. The liquid crystal driver chip outputs a corresponding voltage to each conductive area on the corresponding conductive layer according to the received voltage. The output voltage can drive the liquid crystal state corresponding to the first test area to change to the vertical state, while the states of other areas remain unchanged. For example, V11=60V, V12=20V, V13=0V, and V14=40V. Then, the main control unit controls the voltage generation circuit to output zero voltage to the liquid crystal driver chip. The liquid crystal driver chip rapidly (within 2 milliseconds) reduces the voltage of all conductive layers of the upper and lower films to zero, thereby making the liquid crystal corresponding to the first test area planar, i.e., driving the first test area into display mode. At this time, the illuminance value corresponding to the first test area is measured by the illuminance sensor and recorded as follows: .

[0045] In addition, controlling the voltage difference applied in the first test area to change from small to large is achieved by adjusting the voltage generation signal output by the main control unit to the voltage generation circuit, which is also easily achieved by existing technology.

[0046] Finally, the threshold value can be set according to actual needs; in this embodiment, based on the definition of relative transmittance, the threshold value is determined as: Z min +0.9 (Z) max -Z min This is equivalent to a relative transmittance of not less than 0.9, close to or equal to 100%; that is, the voltage difference corresponding to the first test area has caused the liquid crystal state to change from a planar state to a focal cone state, thus realizing the erasure of the first test area; therefore, the voltage difference formed by the two conductive layers in the first test area can be used as the current erasure voltage of the liquid crystal writing film.

[0047] in, The illuminance value is the illuminance value measured by the illuminance sensor when the liquid crystal in the test area is in a planar state during the same period. It can be measured when the liquid crystal in the aforementioned first test area is in a display state. This refers to the illuminance value measured by the illuminance sensor when the liquid crystal in the test area is in the focal conic state during the same period. The specific testing method is also feasible for those skilled in the art. For example, the main control unit first controls the voltage generation circuit to output a predetermined voltage to the liquid crystal driver chip. The liquid crystal driver chip then outputs a corresponding voltage to each conductive area on the corresponding conductive layer based on the received voltage. Since the voltage difference for erasure using commonly used liquid crystal formulations is typically in the range of 10V to 50V, this embodiment controls the voltage difference corresponding to the first test area to steadily decrease from 50V to 10V (decreasing by 10V each time), with the voltage decrease process lasting no less than 20 milliseconds. This ensures that the measured liquid crystal is always in the focal conic state. At this time, the illuminance value corresponding to the first test area is measured by the illuminance sensor and recorded as... .

[0048] In this embodiment, the main control unit, amplifier circuit, voltage generation circuit, and liquid crystal driver chip can all be set on the main control board of the liquid crystal writing device, and the main control board can be hidden inside the bezel.

[0049] The main control unit initiates a check and adjustment of the erasure voltage every predetermined time period (such as every half hour or every day) or when it receives an external trigger command, thereby ensuring that the LCD writing device always maintains a good local erasure effect.

[0050] Example 2 In one or more embodiments, a liquid crystal writing device is disclosed, comprising: a liquid crystal writing film, a substrate for supporting the liquid crystal writing film, and a main control unit; the specific structure is the same as that in Embodiment 1. The difference is: In this embodiment, a second test area and a third test area were also selected on the liquid crystal writing film.

[0051] Specifically, in combination Figure 4 Within the conductive area covering the first test area on the first conductive layer, a second test area is selected, and the second test area does not overlap with the first test area; an opening is provided on the substrate corresponding to the position of the second test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit.

[0052] And / or, Within the conductive area covering the first test area on the second conductive layer, a third test area is selected, which does not overlap with the first test area; an opening is provided on the substrate corresponding to the third test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit.

[0053] The selection and connection method of the illuminance sensor are exactly the same as in Example 1, and will not be described in detail again.

[0054] In this embodiment, the second test area and the third test area can be set simultaneously, or one of them can be set.

[0055] The purpose of setting up the second and third test areas is to ensure that when the target erasure area (i.e., the first test area) is erased, the writing in the surrounding areas that belong to the same conductive area will not be affected and will not fade or disappear.

[0056] Taking the second and third test areas as an example, the principle for specific erase voltage detection is basically the same as in Example 1, as follows: By applying voltage, the liquid crystals in the first, second, and third test areas are all in a display state. Then, the voltage difference applied to the first test area is controlled to change from small to large, and the illuminance value corresponding to the first test area is recorded for each voltage change. When the illuminance value of the first test area is greater than or equal to the first set threshold, and the illuminance values ​​of the second and third test areas are less than or equal to the second set threshold, it indicates that the first test area has been erased cleanly and the surrounding areas are not affected. At this time, the corresponding voltage difference can be used as the erasure voltage of the current liquid crystal writing film.

[0057] The second threshold can be set as: Z min +0.1 (Z) max -Z min This means that the relative transmittance at this time is no greater than 0.1, which is close to or equal to 0, indicating that the voltage difference between the second and third test areas at this time does not cause the liquid crystal state of the corresponding area to change or only causes a slight change.

[0058] The remaining processes are implemented in the same way as in Example 1, and other parts not mentioned are also the same as in Example 1, and will not be described in detail hereafter.

[0059] Example 3 In one or more embodiments, a liquid crystal writing device is disclosed, comprising: a liquid crystal writing film, a substrate for supporting the liquid crystal writing film, and a main control unit; the specific structure is the same as that in Embodiment 2. The difference is: In this embodiment, a fourth test area was also selected on the liquid crystal writing film.

[0060] Specifically, in combination Figure 5 Based on the second and third test areas selected in Embodiment 2, a fourth test area is selected on the first and second conductive layers, outside the conductive area of ​​the first test area. An opening is provided on the substrate corresponding to the fourth test area, and an illuminance sensor is fixedly installed within the opening; the illuminance sensor is connected to the main control unit.

[0061] The selection and connection method of the illuminance sensor are exactly the same as in Example 2, and will not be described in detail again.

[0062] The purpose of setting up the second, third, and fourth test areas is to ensure that when the target erasure area (i.e., the first test area) is erased, the writing in the same conductive area as it, as well as the surrounding areas of other conductive areas, will not be affected and will not fade or disappear.

[0063] Taking the simultaneous setting of the second and third test areas as an example, the principle is basically the same as in Example 1 when detecting the erase voltage, specifically as follows: By applying voltage, the liquid crystals in the first, second, third, and fourth test areas are all in a display state. Then, the voltage difference applied to the first test area is controlled to change from small to large, and the illuminance value of the first test area is recorded for each voltage change. When the illuminance value of the first test area is greater than or equal to the first set threshold, and the illuminance values ​​of the second, third, and fourth test areas are less than or equal to the second set threshold, it indicates that the first test area has been cleaned and the surrounding areas are not affected. At this time, the corresponding voltage difference can be used as the erasure voltage of the current liquid crystal writing film.

[0064] The specific implementation method of the above process and the setting method of the first and second set thresholds are exactly the same as in Embodiment 2. Other unmentioned parts are also the same as in Embodiment 2 and will not be described in detail.

[0065] Example 4 In one or more embodiments, a liquid crystal writing device is disclosed. Based on the liquid crystal writing device disclosed in Embodiment 1, Embodiment 2, or Embodiment 3, at least one temperature sensor is added, and the temperature sensor is connected to the main control unit. The purpose of setting the temperature sensor is to detect the temperature value of the liquid crystal writing film. When the temperature value changes too much, such as exceeding a preset threshold, the main control unit will automatically start the erasure voltage detection process.

[0066] As an example, the temperature sensor can be placed in the opening corresponding to the first test area, the second test area, the third test area, or the fourth test area, and placed on the same circuit board as the illuminance sensor. As another example, a hole can be made on the substrate separately, and the temperature sensor can be placed inside the hole. The specific fixing method can be the same as that used for fixing an illuminance sensor.

[0067] As another example, the temperature sensor is also placed inside the bezel of the LCD writing device, and a through hole is opened on the bezel at the mounting location to communicate with the outside, so as to ensure that the temperature obtained is accurate and reliable.

[0068] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A liquid crystal writing device, characterized in that, include: A liquid crystal writing film, a substrate for supporting the liquid crystal writing film, and a main control unit; the liquid crystal writing film has a first test area, and the substrate has an opening at a position corresponding to the first test area. An illuminance sensor is fixedly installed in the opening, the illuminance sensor is positioned facing the liquid crystal writing film, and the illuminance sensor is connected to the main control unit.

2. A liquid crystal writing device, characterized in that, include: A liquid crystal writing film, a substrate for supporting the liquid crystal writing film, and a main control unit; the liquid crystal writing film has a first test area, and the substrate has an opening at the position corresponding to the first test area. An illuminance sensor is fixedly installed in the opening, the illuminance sensor is positioned facing the liquid crystal writing film, and the illuminance sensor is connected to the main control unit. It also includes a temperature sensor, which is connected to the main control unit.

3. The liquid crystal writing device as described in claim 2, characterized in that, The temperature sensor is disposed in an opening corresponding to the first test area, the second test area, the third test area, or the fourth test area; or, the temperature sensor is disposed in an opening at another location between the liquid crystal writing film and the substrate; or, the temperature sensor is disposed within the frame of the liquid crystal writing device, and a through hole communicating with the outside is opened on the frame at the corresponding location.

4. A liquid crystal writing device as described in claim 1 or 2, characterized in that, The liquid crystal writing film includes a first conductive layer, a bistable liquid crystal layer, and a second conductive layer disposed sequentially; the first conductive layer and the second conductive layer are respectively divided into multiple mutually insulated and parallel conductive regions, and the conductive regions of the first conductive layer and the conductive regions of the second conductive layer are spatially perpendicular to each other.

5. A liquid crystal writing device as described in claim 4, characterized in that, Within the conductive area covering the first test area on the first conductive layer, a second test area is selected, and the second test area does not overlap with the first test area. An opening is provided on the substrate at the position corresponding to the second test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit. And / or, Within the conductive area covering the first test area on the second conductive layer, a third test area is selected, and the third test area does not overlap with the first test area. An opening is provided on the substrate at the position corresponding to the third test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit.

6. A liquid crystal writing device as described in claim 5, characterized in that, A fourth test area is selected outside the conductive area of ​​the first test area on the first and second conductive layers; An opening is provided on the substrate at the position corresponding to the fourth test area, and an illuminance sensor is fixedly installed in the opening; the illuminance sensor is connected to the main control unit.

7. A liquid crystal writing device as described in claim 1 or 2, characterized in that, The illuminance sensor is fixed on a circuit board, which is in turn fixed on a substrate. The circuit board has a wiring port, which connects to the main control unit.

8. A liquid crystal writing device as described in claim 1 or 2, characterized in that, The illuminance sensor is fixed on the circuit board, the circuit board is fixed on the support, the support is connected to the substrate and extends into the opening; the circuit board is connected to the wiring port, and is connected to the main control unit through the wiring port; the support is provided with a wire outlet hole to lead out the wiring on the circuit board.

9. A liquid crystal writing device as described in claim 1 or 2, characterized in that, The illuminance sensor is a monochrome analog output illuminance sensor or a tricolor analog output illuminance sensor; The signal transmission line of the monochrome analog output illuminance sensor or the tricolor analog output illuminance sensor is led out through the terminal block, connected to the amplifier circuit, and then connected to the AD pin of the main control unit. Alternatively, the illuminance sensor is a three-color digital output illuminance sensor; the signal transmission line of the three-color digital output illuminance sensor is led out through the wiring port and connected to the SPI bus or I2C bus of the main control unit. Alternatively, the illuminance sensor may be a photoresistor.

10. A liquid crystal writing device as described in claim 1 or 2, characterized in that, The first test area is selected at the corner of the liquid crystal writing film.

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