Conveying device for LCD screen testing

Abstract

The invention discloses a conveying device for LCD screen testing, and relates to the technical field of conveying devices. According to the LCD screen conveying device, through mutual cooperation of the threaded groove and the annular groove, an LCD screen on the roller can be automatically centered, and the problems that a conveying device is low in efficiency and cannot flexibly adapt to LCD screens of different sizes and types are solved; the time of damage caused by friction can be calculated through the data processing module according to the friction coefficient between the roller and the LCD screen, the movement speed of the LCD screen and the like, the time is compared with the actual adjustment time and the transmission time, and when it is judged that damage can happen, the data execution module controls the electric push rod, the electrified spring and other components to lift the LCD screen up, and the LCD screen is prevented from being damaged. The LCD screen is not in contact with the roller any more, damage to the LCD screen due to too long friction time is avoided, and the problem that in the prior art, the LCD screen is prone to damage due to friction in the conveying process after being centered is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of conveying devices, and in particular to a conveying device for testing LCD screens. Background Art

[0002] With the widespread application of LCD screens in various electronic devices, the scale of production is constantly expanding, and the requirements for inspection efficiency and quality are also increasing. The sizes and types of LCD screens vary from small screens used in small devices such as mobile phones and tablets to large screens used in large devices such as TVs and monitors. Their shapes, thicknesses, weights and other parameters are different. The conveying device needs to be able to flexibly adapt to LCD screens of different sizes and types, ensure its stability and safety during the conveying process, and meet the requirements of different inspection equipment; However, the existing conveying device for LCD screen testing cannot efficiently and accurately convey the LCD screen to the testing equipment, and cannot flexibly adapt to LCD screens of different sizes and types, and it is difficult to ensure its stability and safety during the conveying process, and it cannot meet the requirement of automatic centering of the conveyed LCD screen; In the prior art, when the LCD screen is conveyed to the center by rollers, the LCD screen still rubs against the rollers after reaching the center position during the conveying process. If the friction time is too long, the LCD screen may be damaged. Therefore, it is necessary to solve the above technical problems. Summary of the invention

[0003] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a conveying device for LCD screen testing.

[0004] In order to achieve the above-mentioned object, the present invention adopts the following technical scheme: a conveying device for testing LCD screens, comprising a support column, the support column is fixedly connected to the lower ends of the guard plates on both sides at equal distances, a cavity structure is provided inside the guard plates, and rollers are installed at equal distances between the guard plates, an automatic centering mechanism is provided outside the rollers, and the rollers are rotatably clamped between the guard plates, and a circulation mechanism is installed inside the guard plates; A control box is also arranged at the position of the drive motor on the outside of the guard plate, and a control component is arranged inside the control box. The control component includes a data acquisition module, a data processing module and a data execution module; The data acquisition module detects the position data of the LCD screen on the roller, the rotation speed and time data of the roller, and transmits the detected position data, speed data and time data to the data processing module; The data processing module determines the position data of the LCD screen to determine whether the LCD screen is in a centered state; processes the roller rotation speed and time data to determine how long the friction between the roller and the LCD screen will cause damage to the LCD screen, and compares the time. When it is determined that damage will occur, a lifting signal is generated and transmitted to the data execution module; The data execution module receives the lifting signal, distinguishes the type of the lifting signal, and performs the lifting operation of the LCD screen according to the signal type.

[0005] Preferably, the circulation mechanism includes driving wheels rotatably mounted at both ends of the inner side of the guard plate, a belt is sleeved on the outer side of the driving wheel, and a driving motor is fixed to the outer side of the guard plate at the same position of the driving wheel by bolts.

[0006] Preferably, the driving shaft of the driving motor passes through the guard plate and is clamped in the middle of one end of the driving wheel, the belts pass through the inner side of the guard plate horizontally, and a plurality of U-shaped fixing buckles are equidistantly fixed to one side of the belt.

[0007] Preferably, a fixing threaded hole is horizontally opened in the middle of the U-shaped fixing buckle, and a push plate is clamped between the U-shaped fixing buckles, and the push plate and the U-shaped fixing buckle are fixedly connected by a hexagon socket bolt.

[0008] Preferably, the automatic centering mechanism comprises thread grooves formed on both sides of the roller, the thread grooves rotate inwardly, and annular grooves are formed on the roller in the middle of the thread grooves at equal distances.

[0009] Preferably, a sliding groove is provided on one side of the outer wall of the push plate, a slider is slidably connected to the inner side of the sliding groove, the outer wall of the slider is rotatably connected to an L-shaped frame through a rotating shaft, the inner ends of the sliding groove are connected to the slider through an electric push rod, a circular groove is provided on the outer wall of the slider at a position corresponding to the L-shaped frame, a battery pack is also installed at a position corresponding to the circular groove inside the slider, and an energized spring is installed at a position corresponding to the L-shaped frame on the inner upper surface of the circular groove.

[0010] Preferably, the data processing steps for the data processing module to perform LCD screen centering determination are as follows: Step 1: Detect the position of the LCD screen and calculate the distance data between the four corners of the LCD screen and the corresponding side guard plates , , and , if the two sets of spacing data on the same side are equal, it is determined that the LCD screen and the guard plate are in a parallel state; Step 2: If only one set of spacing data on the same side is equal, the appearance of the LCD screen is inspected. If the appearance inspection data of the LCD screen is normal, it is determined that the inspection data is incorrect, and the LCD screen position data is re-inspected.

[0011] Preferably, the data processing module performs the following steps to process the data of LCD screen friction damage: Step 1: The friction coefficient between the roller and the LCD screen is , then the friction force on the LCD screen is The LCD screen moves in a uniform linear motion on the roller as the roller rotates, with a speed of v. The power produced by the friction force per unit time is , the work done in time t , when the work done Reaching the preset threshold When the friction is judged to cause damage to the LCD screen, the time required to cause damage is ; Step 2: After adjusting the LCD to the center position, adjust the time data used Perform statistics, and then according to the transmission speed of the conveyor belt Calculate the time required to transfer the LCD screen to the end ,like , then after the LCD screen is centered, a boost signal is immediately generated and passed to the data execution module; if and , then after the LCD screen is centered, a boost signal is immediately generated and passed to the data execution module; if , it is determined that the LCD screen will not be damaged after being transferred to the end, and the lifting operation is not performed; Step 3: Detect the length and width data of the LCD screen, and calculate the difference between the detected length and width data and the distance data between the two guard plates to obtain the distance data between the LCD screen and the two side guard plates after the LCD screen is centered. and ;when or When the LCD screen is in the center, the data processing module generates a boost signal and transmits the boost signal to the data execution module. The data processing module processes the spacing data. and For analysis, if the spacing data is spacing data , then a boost signal 1 is generated; otherwise, a boost signal 2 is generated.

[0012] Preferably, the execution steps of the data execution module are as follows: Step 1: After receiving the boost signal, determine the signal type; Step 2: If the received lifting signal is lifting signal 1, the signal is transmitted to the electric push rod inside the chute, so that the length of the electric push rod is adjusted to the spacing data. If the value of the sum of the preset distance d is consistent, otherwise, the length of the electric push rod is adjusted to the spacing data. The value of the sum of the two is consistent with the preset distance d; Step 3: After the length of the electric push rod is adjusted, the data execution module controls the control switch to cut off the power to the energized spring, so that the energized spring after power off pushes the L-shaped frame to rotate around the shaft during the pop-up process, and the lower end of the L-shaped frame lifts the LCD screen during the downward rotation process, so that the LCD screen is lifted up by the action of the four L-shaped frames on the two push plates. After being lifted, the LCD screen no longer contacts the roller, so that the LCD screen will not rub against the roller.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The belt and the push plate cooperate with each other to quickly transport the LCD screen to the testing equipment, which improves the efficiency of the conveying device and realizes the function of rapid transportation. The screw groove and the annular groove cooperate with each other to make the LCD screen on the roller automatically centered, which improves the stability of LCD screen transportation and realizes the function of automatic centering of the LCD screen. Finally, the problem of low efficiency of the conveying device and the inability to flexibly adapt to LCD screens of different sizes and types is solved; 2. The data acquisition module detects the position data of the LCD screen on the roller, the roller rotation speed and time data. The data processing module determines whether the LCD screen is centered by calculating the distance data between the four corners of the LCD screen and the corresponding side guard plates. If it is not centered, it can be adjusted in time, thereby improving the accuracy and stability of the LCD screen position during the conveying process; 3. The data processing module can calculate the time of damage caused by friction based on the friction coefficient between the roller and the LCD screen, the movement speed of the LCD screen, etc., and compare it with the actual adjustment time and transmission time. When it is determined that damage will occur, the data execution module controls the electric push rod and the energized spring and other components to lift the LCD screen so that the LCD screen no longer contacts the roller, thereby avoiding damage to the LCD screen due to excessive friction time, and solving the problem in the prior art that the LCD screen is easily damaged due to friction during the transportation process after centering. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a schematic diagram of the overall three-dimensional structure proposed by the present invention; Figure 2 This is a schematic diagram of the overall three-dimensional structure when viewed from above proposed by the present invention; Figure 3A schematic diagram of the top view structure of the present invention; Figure 4 This is a schematic diagram of the overall three-dimensional structure of the other side of the local part proposed by the present invention; Figure 5 The present invention proposes Figure 4 A schematic diagram of the enlarged structure in the middle; Figure 6 A side cross-sectional structural schematic diagram of the present invention; Figure 7 It is a system flow chart of the present invention.

[0015] Serial numbers in the figure: 1. Support column; 2. Guard plate; 3. Drive motor; 4. Roller; 5. Thread groove; 6. Ring groove; 7. Belt; 8. Push plate; 9. U-shaped fixing buckle; 10. Hexagon socket bolt; 11. Driving wheel. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0017] Example: See Figure 1-7 A conveying device for testing an LCD screen in the present invention comprises a support column 1, which is fixedly connected to the lower ends of guard plates 2 on both sides at equal distances, a cavity structure is provided on the inner side of the guard plates 2, and rollers 4 are installed equidistantly between the guard plates 2, an automatic centering mechanism is provided on the outer side of the rollers 4, and the rollers 4 are rotatably connected between the guard plates 2, and a circulation mechanism is installed on the inner side of the guard plates 2, so that the LCD screen can be stably conveyed through the guard plates 2 and the rollers 4; the circulation mechanism comprises a driving wheel 11 rotatably installed at both ends of the inner side of the guard plates 2, a belt 7 is sleeved on the outer side of the driving wheel 11, and a driving motor 3 is fixedly installed on the outer side of the guard plate 2 at the same position of the driving wheel 11 by bolts, so that the belt 7 can be circulated through the driving wheel 11 and the belt 7.

[0018] A slide groove is provided on one side of the outer wall of the push plate 8, and a slider is slidably connected to the inner side of the slide groove. The outer wall of the slider is rotatably connected to the L-shaped frame through a rotating shaft. The two ends of the inner side of the slide groove are connected to the slider through an electric push rod, and the position of the slider on the slide groove is controlled by changing the length of the electric push rod. A circular groove is provided at the outer wall of the slider corresponding to the position of the L-shaped frame, and a battery pack is also installed at the position of the circular groove inside the slider corresponding to the position of the circular groove. An energized spring is installed on the upper surface of the inner part of the circular groove corresponding to the position of the L-shaped frame. The other end of the energized spring is connected to the lower end of the L-shaped frame. The battery pack performs energization and de-energization operations on the energized spring under the control of the control switch. The energized spring is energized and contracts, driving the lower end of the L-shaped frame to rotate upward, so that the lower end of the L-shaped frame is closest to the connection position of the energized spring. The energized spring rebounds when the power is turned off, so that the lower end of the L-shaped frame is farthest from the connection position of the energized spring and maintains a vertical state with the push plate 8; A control box is also provided on the outside of the guard plate 2 at the position corresponding to the driving motor 3, and a control component is provided inside the control box. The control component includes a data acquisition module, a data processing module and a data execution module; Detect the position of the LCD screen and calculate the distance data between the four corners of the LCD screen and the corresponding side guard plate 2 , , and If the two sets of spacing data on the same side are equal, it is determined that the LCD screen and the guard plate 2 are in a parallel state; if only one set of spacing data on the same side is equal, the appearance of the LCD screen is tested. If the appearance test data of the LCD screen is normal, it is determined that the test data is wrong, and the LCD screen position data is tested again; The LCD screen moves on the roller 4 by mutual friction with the roller 4. When the LCD screen is not centered, the weight of the LCD screen on one side is greater than that on the other side, that is, the friction force on one side is greater than that on the other side. When the friction force between the LCD screen and the roller 4 acts, there is a force pushing the LCD screen to the other side. The friction coefficient between roller 4 and LCD screen is , then the friction force on the LCD screen is The LCD screen moves in a uniform linear motion on roller 4 as roller 4 rotates, with a speed of v. The power produced by the friction force per unit time is , the work done in time t , when the work done Reaching the preset threshold When the friction is judged to cause damage to the LCD screen, the time required to cause damage is ; After adjusting the LCD to the center position, the time data used for adjustment Perform statistics, and then according to the transmission speed of the conveyor belt Calculate the time required to transfer the LCD screen to the end ,like , then after the LCD screen is centered, a boost signal is immediately generated and passed to the data execution module; if and , then after the LCD screen is centered, a boost signal is immediately generated and passed to the data execution module; if , it is determined that the LCD screen will not be damaged after being transferred to the end, and the lifting operation is not performed; Detect the length and width data of the LCD screen, and calculate the difference between the detected length and width data and the distance data between the two guard plates 2 to obtain the distance data between the LCD screen and the guard plates 2 on both sides after the LCD screen is centered. and ;when or When the LCD screen is in the center, the data processing module generates a boost signal and transmits the boost signal to the data execution module. The data processing module processes the spacing data. and For analysis, if the spacing data is spacing data , then the boost signal 1 is generated; otherwise, the boost signal 2 is generated; After receiving the lifting signal, the data execution module determines the signal type; if the received lifting signal is lifting signal 1, it transmits the signal to the electric push rod inside the slide slot, so that the length of the electric push rod is adjusted to the spacing data. If the value of the sum of the preset distance d is consistent, otherwise, the length of the electric push rod is adjusted to the spacing data. The value of the sum of the two is consistent with the preset distance d; after the length adjustment of the electric push rod is completed, the data execution module controls the control switch to de-energize the energized spring, so that the energized spring after de-energization pushes the L-shaped frame to rotate around the rotating shaft during the pop-up process, and the lower end of the L-shaped frame lifts the LCD screen during the downward rotation process, so that the LCD screen is lifted up under the action of the four L-shaped frames on the two push plates 8, and the lifted LCD screen no longer contacts the roller 4, so that the LCD screen and the roller 4 will not rub against each other.

[0019] In the present invention, the driving shaft of the driving motor 3 passes through the guard plate 2 and is clamped in the middle of one end of the driving wheel 11, so that the driving motor 3 can easily drive the belt 7 to rotate through the driving wheel 11; the belt 7 passes through the inner side of the guard plate 2 horizontally, and a plurality of U-shaped fixing buckles 9 are fixedly connected to one side of the belt 7 at equal distances, and the LCD screen push plate is conveniently installed through the belt 7 and the U-shaped fixing buckle 9; the middle part of the U-shaped fixing buckle 9 is horizontally provided with a fixed threaded hole, and a push plate 8 is clamped between the U-shaped fixing buckles 9, and the push plate 8 and the U-shaped fixing buckle 9 are fixedly connected by an inner hexagonal bolt 10, and the push plate 8 and the U-shaped fixing buckle 9 are convenient to make one end of the LCD screen fit closely with one end of the push plate 8; the automatic centering mechanism includes threaded grooves 5 opened on both sides of the roller 4, the threaded grooves 5 rotate inwardly, and annular grooves 6 are evenly opened on the roller 4 in the middle of the threaded grooves 5, and the threaded grooves 5 and the annular grooves 6 can facilitate the automatic centering of the LCD screen during the conveying process.

[0020] Working principle: When the present invention is used, the support column 1 and the guard plate 2 are first used to form a frame of the conveying device, and then the driving motor 3 is used to drive the driving wheel 11 inside the guard plate 2 to rotate, and then the driving wheel 11 drives the outer belt 7 to move in a circular motion, and then the U-shaped fixing buckle 9 and the hexagon socket bolt 10 are used to fix the push plate 8 between the belts 7, and then the roller 4 between the guard plates 2 is used to drive the push plate 8 to rotate through the belt 7 to push the LCD screen on the roller 4, and then the threaded grooves 5 at both ends of the roller 4 are used to move the LCD screen on the roller 4 toward the center, and then the circular groove 6 is used to make the LDC screen move smoothly in the center; After the LCD screen is centered, the data analysis module processes and analyzes the spacing data between the LCD screen and the two side guard plates 2, and generates a lifting signal, and transmits the lifting signal to the data execution module, which distinguishes the received lifting signal; if the received lifting signal is lifting signal 1, the signal is transmitted to the electric push rod inside the slide slot, so that the length of the electric push rod is adjusted to match the spacing data. If the value of the sum of the preset distance d is consistent, otherwise, the length of the electric push rod is adjusted to the spacing data. The value of the sum of the two is consistent with the value of the preset distance d; after the length adjustment of the electric push rod is completed, the data execution module controls the control switch to de-energize the energized spring, so that the energized spring after de-energization pushes the L-shaped frame to rotate around the rotating shaft during the pop-up process, and the lower end of the L-shaped frame lifts the LCD screen during the downward rotation process, so that the LCD screen is lifted up under the action of the four L-shaped frames on the two push plates 8, and the lifted LCD screen no longer contacts the roller 4, so that the LCD screen and the roller 4 will not rub against each other; When the LCD screen is about to be transferred to the end position of the conveyor belt, the data execution module transmits a signal to control the control switch to energize the power spring, and the power spring contracts after being energized, and the lifted LCD screen is placed back on the roller 4.

[0021] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A conveying device for testing an LCD screen, comprising a support column (1), characterized in that: The support column (1) is fixedly connected to the lower ends of the guard plates (2) on both sides at equal distances, a cavity structure is provided inside the guard plates (2), and rollers (4) are installed at equal distances between the guard plates (2), an automatic centering mechanism is provided outside the rollers (4), and the rollers (4) are rotatably clamped between the guard plates (2), and a circulation mechanism is installed inside the guard plates (2); A control box is also provided at the position of the drive motor (3) on the outer side of the guard plate (2), and a control component is provided inside the control box. The control component includes a data acquisition module, a data processing module and a data execution module; A data acquisition module detects the position data of the LCD screen on the roller (4), detects the rotation speed and time data of the roller (4), and transmits the detected position data, speed data and time data to the data processing module; The data processing module determines the position data of the LCD screen to determine whether the LCD screen is in a centered state; processes the rotation speed and time data of the roller (4) to determine how long the friction between the roller (4) and the LCD screen will cause damage to the LCD screen, and compares the time. When it is determined that damage will occur, a lifting signal is generated, and the lifting signal is transmitted to the data execution module; The data execution module receives the lifting signal, distinguishes the type of the lifting signal, and performs the lifting operation of the LCD screen according to the signal type.

2. The conveying device for LCD screen testing according to claim 1, characterized in that: The circulation mechanism comprises a driving wheel (11) rotatably mounted at both ends of the inner side of the guard plate (2), a belt (7) being sleeved on the outer side of the driving wheel (11), and a driving motor (3) being fixedly mounted on the outer side of the guard plate (2) at the same position as the driving wheel (11) by means of bolts.

3. The conveying device for LCD screen testing according to claim 2, characterized in that: The drive shaft of the drive motor (3) passes through the guard plate (2) and is clamped in the middle of one end of the driving wheel (11). The belts (7) all pass through the inner side of the guard plate (2) horizontally, and a plurality of U-shaped fixing buckles (9) are fixedly connected at equal intervals on one side of the belt (7).

4. The conveying device for LCD screen testing according to claim 3, characterized in that: The U-shaped fixing buckles (9) are all provided with fixing threaded holes in the middle thereof, and push plates (8) are clamped between the U-shaped fixing buckles (9). The push plates (8) and the U-shaped fixing buckles (9) are fixedly connected by hexagon socket bolts (10).

5. The conveying device for LCD screen testing according to claim 4, characterized in that: The automatic centering mechanism comprises thread grooves (5) formed on both sides of the roller (4), the thread grooves (5) all rotate inwards, and annular grooves (6) are formed on the roller (4) at equal intervals in the middle of the thread grooves (5).

6. The conveying device for LCD screen testing according to claim 5, characterized in that: A sliding groove is provided on one side of the outer wall of the push plate (8), a slider is slidably connected to the inner side of the sliding groove, the outer wall of the slider is rotatably connected to the L-shaped frame via a rotating shaft, the inner ends of the sliding groove are connected to the slider via electric push rods, a circular groove is provided on the outer wall of the slider at a position corresponding to the L-shaped frame, a battery pack is installed at a position corresponding to the circular groove inside the slider, and an energized spring is installed at a position corresponding to the L-shaped frame on the inner upper surface of the circular groove.

7. The conveying device for LCD screen testing according to claim 6, characterized in that: The data processing steps of the data processing module for determining the centering of the LCD screen are as follows: Step 1: Detect the position of the LCD screen and calculate the distance data between the four corners of the LCD screen and the corresponding side guard plate (2) , , and If the two sets of spacing data on the same side are equal, it is determined that the LCD screen and the guard plate (2) are in a parallel state; Step 2: If only one set of spacing data on the same side is equal, the appearance of the LCD screen is inspected. If the appearance inspection data of the LCD screen is normal, it is determined that the inspection data is incorrect, and the LCD screen position data is re-inspected.

8. The conveying device for LCD screen testing according to claim 7, characterized in that: The steps of data processing module for LCD screen friction damage data processing are as follows: Step 1: The friction coefficient between the roller (4) and the LCD screen is , then the friction force on the LCD screen is , the LCD screen moves in a uniform linear motion on the roller (4) as the roller (4) rotates, with a speed of v. Then the power exerted by the friction force per unit time is , the work done in time t , when the work done Reaching the preset threshold When the friction is judged to cause damage to the LCD screen, the time required to cause damage is ; Step 2: After adjusting the LCD to the center position, adjust the time data used Statistics are performed, and then according to the transmission speed of the conveyor belt Calculate the time required to transfer the LCD screen to the end ,like , then after the LCD screen is centered, a boost signal is immediately generated and passed to the data execution module; if and , then after the LCD screen is centered, a boost signal is immediately generated and passed to the data execution module; if , it is determined that the LCD screen will not be damaged after being transferred to the end, and the lifting operation is not performed; Step 3: Detect the length and width data of the LCD screen, and calculate the difference between the detected length and width data and the distance data between the two guard plates (2), and obtain the distance data between the LCD screen and the two side guard plates (2) after the LCD screen is centered. and ;when or When the LCD screen is in the center, the data processing module generates a boost signal and transmits the boost signal to the data execution module. The data processing module processes the spacing data. and For analysis, if the spacing data is spacing data , then a boost signal 1 is generated; otherwise, a boost signal 2 is generated.

9. The conveying device for LCD screen testing according to claim 8, characterized in that: The execution steps of the data execution module are as follows: Step 1: After receiving the boost signal, determine the signal type; Step 2: If the received lifting signal is lifting signal 1, the signal is transmitted to the electric push rod inside the chute, so that the length of the electric push rod is adjusted to the spacing data. If the value of the sum of the preset distance d is consistent, otherwise, the length of the electric push rod is adjusted to the spacing data. The value of the sum of the two is consistent with the preset distance d; Step 3: After the length of the electric push rod is adjusted, the data execution module controls the control switch to de-energize the energized spring, so that the energized spring after de-energization pushes the L-shaped frame to rotate around the rotation axis during the ejection process. The lower end of the L-shaped frame lifts the LCD screen during the downward rotation process, so that the LCD screen is lifted under the action of the four L-shaped frames on the two push plates (8). After being lifted, the LCD screen no longer contacts the roller (4), so that the LCD screen and the roller (4) will not rub against each other.

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